A solid-state drive (SSD), or solid-state disk is a
solid-state storage device that uses integrated circuit assemblies as
memory to store data persistently. SSD technology primarily uses
electronic interfaces compatible with traditional block input/output
(I/O) hard disk drives (HDDs), which permit simple replacements in
common applications. New I/O interfaces like
SATA Express and M.2
have been designed to address specific requirements of the SSD
SSDs have no moving mechanical components. This distinguishes them
from traditional electromechanical drives such as hard disk drives
(HDDs) or floppy disks, which contain spinning disks and movable
read/write heads. Compared with electromechanical drives, SSDs are
typically more resistant to physical shock, run silently, have quicker
access time and lower latency. However, while the price of SSDs has
continued to decline over time SSDs are (as of 2018[update]) still
more expensive per unit of storage than HDDs and are expected to
continue so into the next decade.
As of 2017[update], most SSDs use 3D TLC NAND-based flash memory,
which is a type of non-volatile memory that retains data when power is
lost. For applications requiring fast access but not necessarily data
persistence after power loss, SSDs may be constructed from
random-access memory (RAM). Such devices may employ batteries as
integrated power sources to retain data for a certain amount of time
after external power is lost.
However, all SSDs still store data in electrical charges, which slowly
leak over time if left without power. This causes worn out drives
(that have exceeded their endurance rating) to start losing data
typically after one (if stored at 30°C) to two (at 25°C) years in
storage; for new drives it takes longer. Therefore, SSDs are not
suited for archival purposes.
Hybrid drives or solid-state hybrid drives (SSHDs) combine the
features of SSDs and HDDs in the same unit, containing a large hard
disk drive and an SSD cache to improve performance of frequently
1 Development and history
1.1 Early SSDs using RAM and similar technology
1.2 Flash-based SSDs
1.3 Enterprise flash drives
2 Architecture and function
2.3 Cache or buffer
2.4 Wear leveling
2.5 Battery or supercapacitor
2.6 Host interface
3.1 Standard HDD form factors
3.2 Standard card form factors
3.3 Disk-on-a-module form factors
3.4 Box form factors
3.5 Bare-board form factors
3.6 Ball grid array form factors
4 Comparison with other technologies
4.1 Hard disk drives
4.2 Memory cards
5 SSD failure
5.1 SSD reliability and failure modes
Data recovery and secure deletion
6.1 Hard drives caching
File system support for SSDs
Linux performance considerations
7.2 OS X
7.3.1 Windows 7 and later
7.3.2 Windows Vista
7.6 Swap partitions
8 Standardization organizations
9.2 Quality and performance
10 See also
12 Further reading
13 External links
Development and history
Early SSDs using RAM and similar technology
An early if not first semiconductor storage device compatible with a
hard drive interface (e.g. an SSD as defined) was the 1978 StorageTek
4305. The StorageTek 4305, a plug-compatible replacement for the IBM
2305 fixed head disk drive, initially used charged coupled devices for
storage and consequently was reported to be seven times faster than
the IBM product at about half the price. It later switched to
Prior to the StorageTek SSD there were many
DRAM and core (e.g.
DATARAM BULK Core, 1976) products sold as alternatives to HDDs but
these products typically had memory interfaces and were not SSDs as
In the late 1980s Zitel, Inc., offered a family
DRAM based SSD
products, under the trade name "RAMDisk," for use on systems by UNIVAC
and Perkin-Elmer, among others.
SanDisk Corporation (then SunDisk) shipped the first SSD, a
20 MB solid state drive (SSD) which sold OEM for around $1,000.
It was used by IBM in a
STEC, Inc. entered the flash memory business for consumer
M-Systems introduced flash-based solid-state drives as
HDD replacements for the military and aerospace industries, as well as
for other mission-critical applications. These applications require
the exceptional mean time between failures (MTBF) rates that
solid-state drives achieve, by virtue of their ability to withstand
extreme shock, vibration and temperature ranges.
In 1999, BiTMICRO made a number of introductions and announcements
about flash-based SSDs, including an 18 GB 3.5-inch SSD.
Fusion-io announced a PCIe-based Solid state drive with
100,000 input/output operations per second (IOPS) of performance
in a single card, with capacities up to 320 gigabytes.
At Cebit 2009,
OCZ Technology demonstrated a 1 terabyte (TB)
flash SSD using a
PCI Express ×8 interface. It achieved a maximum
write speed of 654 megabytes per second (MB/s) and maximum read
speed of 712 MB/s.
In December 2009,
Micron Technology announced an SSD using a
6 gigabits per second (Gbit/s)
Enterprise flash drives
Top and bottom views of a 2.5-inch 100 GB SATA 3.0
(6 Gbit/s) model of the
Intel DC S3700 series
Enterprise flash drives (EFDs) are designed for applications requiring
high I/O performance (IOPS), reliability, energy efficiency and, more
recently, consistent performance. In most cases, an EFD is an SSD with
a higher set of specifications, compared with SSDs that would
typically be used in notebook computers. The term was first used by
EMC in January 2008, to help them identify SSD manufacturers who would
provide products meeting these higher standards. There are no
standards bodies who control the definition of EFDs, so any SSD
manufacturer may claim to produce EFDs when in fact the product may
not actually meet any particular requirements.
An example is the
Intel DC S3700 series of drives, introduced in
the fourth quarter of 2012, which focuses on achieving consistent
performance, an area that had previously not received much attention
Intel claimed was important for the enterprise market. In
Intel claims that, at a steady state, the S3700 drives
would not vary their
IOPS by more than 10–15%, and that 99.9% of all
4 KB random I/Os are serviced in less than 500 µs.
Another example is the
Toshiba PX02SS enterprise SSD series, announced
in 2016, which is optimized for use in server and storage platforms
requiring high endurance from write-intensive applications such as
write caching, I/O acceleration and online transaction processing
(OLTP). The PX02SS series uses 12 Gbit/s SAS interface, featuring
NAND flash memory and achieving random write speeds of up to
42,000 IOPS, random read speeds of up to 130,000 IOPS, and endurance
rating of 30 drive writes per day (DWPD).
Architecture and function
The key components of an SSD are the controller and the memory to
store the data. The primary memory component in an SSD was
DRAM volatile memory, but since 2009 it is more commonly
NAND flash non-volatile memory.
Every SSD includes a controller that incorporates the electronics that
bridge the NAND memory components to the host computer. The controller
is an embedded processor that executes firmware-level code and is one
of the most important factors of SSD performance. Some of the
functions performed by the controller include:
Bad block mapping
Read and write caching
Error detection and correction via
Error-correcting code (ECC)
Read scrubbing and read disturb management
The performance of an SSD can scale with the number of parallel NAND
flash chips used in the device. A single NAND chip is relatively slow,
due to the narrow (8/16 bit) asynchronous I/O interface, and
additional high latency of basic I/O operations (typical for SLC NAND,
~25 μs to fetch a 4 KB page from the array to the I/O
buffer on a read, ~250 μs to commit a 4 KB page from the IO
buffer to the array on a write, ~2 ms to erase a 256 KB
block). When multiple NAND devices operate in parallel inside an SSD,
the bandwidth scales, and the high latencies can be hidden, as long as
enough outstanding operations are pending and the load is evenly
distributed between devices.
Intel initially made faster SSDs by implementing data
striping (similar to
RAID 0) and interleaving in their architecture.
This enabled the creation of ultra-fast SSDs with 250 MB/s
effective read/write speeds with the
SATA 3 Gbit/s interface in
2009. Two years later,
SandForce continued to leverage this
parallel flash connectivity, releasing consumer-grade SATA
6 Gbit/s SSD controllers which supported 500 MB/s read/write
SandForce controllers compress the data prior to sending
it to the flash memory. This process may result in less writing and
higher logical throughput, depending on the compressibility of the
Comparison of architectures
MLC : SLC
NAND : NOR
1 : 10
1 : 10
Sequential write ratio
1 : 3
1 : 4
Sequential read ratio
1 : 1
1 : 5
1 : 1.3
1 : 0.7
Most SSD manufacturers use non-volatile
NAND flash memory in the
construction of their SSDs because of the lower cost compared with
DRAM and the ability to retain the data without a constant power
supply, ensuring data persistence through sudden power
Flash memory SSDs are slower than
DRAM solutions, and
some early designs were even slower than HDDs after continued use.
This problem was resolved by controllers that came out in 2009 and
Flash memory-based solutions are typically packaged in standard disk
drive form factors (1.8-, 2.5-, and 3.5-inch), but also in smaller
unique and compact layouts made possible by the small size of flash
Lower-priced drives usually use triple-level cell (TLC) or multi-level
cell (MLC) flash memory, which is slower and less reliable than
single-level cell (SLC) flash memory. This can be mitigated or
even reversed by the internal design structure of the SSD, such as
interleaving, changes to writing algorithms, and higher
over-provisioning (more excess capacity) with which the wear-leveling
algorithms can work.
I-RAM and Hyperdrive (storage)
SSDs based on volatile memory such as
DRAM are characterized by very
fast data access, generally less than 10 microseconds, and are
used primarily to accelerate applications that would otherwise be held
back by the latency of flash SSDs or traditional HDDs.
DRAM-based SSDs usually incorporate either an internal battery or an
external AC/DC adapter and backup storage systems to ensure data
persistence while no power is being supplied to the drive from
external sources. If power is lost, the battery provides power while
all information is copied from random access memory (RAM) to back-up
storage. When the power is restored, the information is copied back to
the RAM from the back-up storage, and the SSD resumes normal operation
(similar to the hibernate function used in modern operating
SSDs of this type are usually fitted with
DRAM modules of the same
type used in regular PCs and servers, which can be swapped out and
replaced by larger modules. Such as i-RAM, HyperOs HyperDrive,
DDRdrive X1, etc. Some manufacturers of
DRAM SSDs solder the DRAM
chips directly to the drive, and do not intend the chips to be swapped
out—such as ZeusRAM, Aeon Drive, etc.
A remote, indirect memory-access disk (RIndMA Disk) uses a secondary
computer with a fast network or (direct)
Infiniband connection to act
like a RAM-based SSD, but the new, faster, flash-memory based, SSDs
already available in 2009 are making this option not as cost
While the price of
DRAM continues to fall, the price of Flash memory
falls even faster. The "Flash becomes cheaper than DRAM" crossover
point occurred approximately 2004.
Some SSDs, called
NVDIMM or Hyper DIMM devices, use both
flash memory. When the power goes down, the SSD copies all the data
DRAM to flash; when the power comes back up, the SSD copies
all the data from its flash to its DRAM. In a somewhat similar
way, some SSDs use form factors and buses actually designed for DIMM
modules, while using only flash memory and making it appear as if it
were DRAM. Such SSDs are usually known as UltraDIMM devices.
Drives known as hybrid drives or solid-state hybrid drives (SSHDs) use
a hybrid of spinning disks and flash memory. Some SSDs use
magnetoresistive random-access memory (MRAM) for storing data.
Intel and Micron announced
3D XPoint as a new non-volatile
Intel plans to produce
3D XPoint SSDs with PCI
Express interface in 2016, which will operate faster and with
higher endurance than NAND-based SSDs, while the areal density will be
comparable at 128 gigabits per chip. For the
price per bit,
3D XPoint will be more expensive than NAND, but cheaper
Cache or buffer
A flash-based SSD typically use a small amount of
DRAM as a volatile
cache, similar to the buffers in hard disk drives. A directory of
block placement and wear leveling data is also kept in the cache while
the drive is operating. One SSD controller manufacturer,
SandForce, does not use an external
DRAM cache on their designs but
still achieves high performance. Such an elimination of the external
DRAM reduces the power consumption and enables further size reduction
Wear leveling and Write amplification
If a particular block was programmed and erased repeatedly without
writing to any other blocks, that block would wear out before all the
other blocks — thereby prematurely ending the life of the SSD. For
this reason, SSD controllers use a technique called wear leveling to
distribute writes as evenly as possible across all the flash blocks in
In a perfect scenario, this would enable every block to be written to
its maximum life so they all fail at the same time. Unfortunately, the
process to evenly distribute writes requires data previously written
and not changing (cold data) to be moved, so that data which are
changing more frequently (hot data) can be written into those blocks.
Each time data are relocated without being changed by the host system,
this increases the write amplification and thus reduces the life of
the flash memory. The key is to find an optimum algorithm which
maximizes them both.
Battery or supercapacitor
Another component in higher-performing SSDs is a capacitor or some
form of battery, which are necessary to maintain data integrity so the
data in the cache can be flushed to the drive when power is lost; some
may even hold power long enough to maintain data in the cache until
power is resumed. In the case of MLC flash memory, a problem
called lower page corruption can occur when MLC flash memory loses
power while programming an upper page. The result is that data written
previously and presumed safe can be corrupted if the memory is not
supported by a supercapacitor in the event of a sudden power loss.
This problem does not exist with SLC flash memory.
Most consumer-class SSDs do not have built-in batteries or
capacitors; among the exceptions are the Crucial M500 and MX100
Intel 320 series, and the more expensive
and 730 series. Enterprise-class SSDs, such as the Intel
DC S3700 series, usually have built-in batteries or
An SSD with 1.2 TB of MLC NAND, using
PCI Express as the host
The host interface is physically a connector with the signalling
managed by the SSD's controller. It is most often one of the
interfaces found in HDDs. They include:
Serial attached SCSI
Serial attached SCSI (SAS, 12.0 Gbit/s) – generally found
Serial ATA (SATA, 6.0 Gbit/s)
PCI Express (PCIe, 31.5 Gbit/s)
Fibre Channel (128 Gbit/s) – almost exclusively found on
USB (10 Gbit/s)
Parallel ATA (UDMA, 1064 Mbit/s) – mostly replaced by
SCSI (> 40 Mbit/s) – generally found
on servers, mostly replaced by SAS; last SCSI-based SSD was introduced
SSDs support various logical device interfaces, such as the original
Advanced Host Controller Interface (AHCI),
NVM Express (NVMe),
and other proprietary interfaces. Logical device interfaces define the
command sets used by operating systems to communicate with SSDs and
host bus adapters (HBAs).
The size and shape of any device is largely driven by the size and
shape of the components used to make that device. Traditional HDDs and
optical drives are designed around the rotating platter(s) or optical
disc along with the spindle motor inside. If an SSD is made up of
various interconnected integrated circuits (ICs) and an interface
connector, then its shape is no longer limited to the shape of
rotating media drives. Some solid state storage solutions come in a
larger chassis that may even be a rack-mount form factor with numerous
SSDs inside. They would all connect to a common bus inside the chassis
and connect outside the box with a single connector.
For general computer use, the 2.5-inch form factor (typically found in
laptops) is the most popular. For desktop computers with 3.5-inch hard
disk drive slots, a simple adapter plate can be used to make such a
drive fit. Other types of form factors are more common in enterprise
applications. An SSD can also be completely integrated in the other
circuitry of the device, as in the Apple
MacBook Air (starting with
the fall 2010 model). As of 2014[update], m
factors are also gaining popularity, primarily in laptops.
Standard HDD form factors
The benefit of using a current
HDD form factor
HDD form factor would be to take
advantage of the extensive infrastructure already in place to mount
and connect the drives to the host system. These traditional
form factors are known by the size of the rotating media, e.g.,
5.25-inch, 3.5-inch, 2.5-inch, 1.8-inch, not by the dimensions of the
Standard card form factors
Main articles: m
SATA and M.2
For applications where space is at premium, like for ultrabooks or
tablet computers, a few compact form factors were standardized for
There is the m
SATA form factor, which uses the
PCI Express Mini Card
physical layout. It remains electrically compatible with the PCI
Express Mini Card interface specification, while requiring an
additional connection to the
SATA host controller through the same
M.2 form factor, formerly known as the Next Generation Form Factor
(NGFF), is a natural transition from the m
SATA and physical layout it
used, to a more usable and more advanced form factor. While m
advantage of an existing form factor and connector,
M.2 has been
designed to maximize usage of the card space, while minimizing the
M.2 standard allows both
PCI Express SSDs to
be fitted onto
Disk-on-a-module form factors
A 2 GB disk-on-a-module with PATA interface
A disk-on-a-module (DOM) is a flash drive with either 40/44-pin
Parallel ATA (PATA) or
SATA interface, intended to be plugged directly
into the motherboard and used as a computer hard disk drive (HDD). DOM
devices emulate a traditional hard disk drive, resulting in no need
for special drivers or other specific operating system support. DOMs
are usually used in embedded systems, which are often deployed in
harsh environments where mechanical HDDs would simply fail, or in thin
clients because of small size, low power consumption and silent
As of 2016[update], storage capacities range from 64 GB to
128 GB with different variations in physical layouts, including
vertical or horizontal orientation.
Box form factors
Many of the DRAM-based solutions use a box that is often designed to
fit in a rack-mount system. The number of
DRAM components required to
get sufficient capacity to store the data along with the backup power
supplies requires a larger space than traditional HDD form
Bare-board form factors
SATA Cube and AMP
SATA Bridge multi-layer SSDs
Viking Technology SATADIMM based SSD
SATA disk-on-a-module (DOM) SSD form factor
Form factors which were more common to memory modules are now being
used by SSDs to take advantage of their flexibility in laying out the
components. Some of these include PCIe, mini PCIe, mini-DIMM, MO-297,
and many more. The SATADIMM from Viking Technology uses an empty
DDR3 DIMM slot on the motherboard to provide power to the SSD with a
SATA connector to provide the data connection back to the
computer. The result is an easy-to-install SSD with a capacity equal
to drives that typically take a full 2.5-inch drive bay. At least
one manufacturer, Innodisk, has produced a drive that sits directly on
SATA connector (SATADOM) on the motherboard without any need for a
power cable. Some SSDs are based on the
PCIe form factor and
connect both the data interface and power through the
to the host. These drives can use either direct
controllers or a PCIe-to-
SATA bridge device which then connects to
SATA flash controllers.
Ball grid array form factors
In the early 2000s, a few companies introduced SSDs in Ball Grid Array
(BGA) form factors, such as M-Systems' (now SanDisk) DiskOnChip
and Silicon Storage Technology's NANDrive (now produced by
Greenliant Systems), and Memoright's M1000 for use in embedded
systems. The main benefits of BGA SSDs are their low power
consumption, small chip package size to fit into compact subsystems,
and that they can be soldered directly onto a system motherboard to
reduce adverse effects from vibration and shock.
Comparison with other technologies
Hard disk drives
SSD benchmark, showing about 230 MB/s reading speed (blue),
210 MB/s writing speed (red) and about 0.1 ms seek time
(green), all independent from the accessed disk location.
Hard disk drive
Hard disk drive performance characteristics
Making a comparison between SSDs and ordinary (spinning) HDDs is
difficult. Traditional SSD benchmarks tend to focus on the performance
characteristics that are poor with HDDs, such as rotational latency
and seek time. As SSDs do not need to spin or seek to locate data,
they may prove vastly superior to HDDs in such tests. However, SSDs
have challenges with mixed reads and writes, and their performance may
degrade over time. SSD testing must start from the (in use) full
drive, as the new and empty (fresh, out-of-the-box) drive may have
much better write performance than it would show after only weeks of
Most of the advantages of solid-state drives over traditional hard
drives are due to their ability to access data completely
electronically instead of electromechanically, resulting in superior
transfer speeds and mechanical ruggedness. On the other hand, hard
disk drives offer significantly higher capacity for their
Field failure rates indicate that SSDs are significantly more reliable
than HDDs. However, SSDs are uniquely sensitive to sudden
power interruption, resulting in aborted writes or even cases of the
complete loss of the drive. The reliability of both HDDs and SSDs
varies greatly among models.
As with HDDs, there is a tradeoff between cost and performance of
Single-level cell (SLC) SSDs, while significantly more
expensive than multi-level (MLC) SSDs, offer a significant speed
advantage. At the same time, DRAM-based solid-state storage is
currently considered the fastest and most costly, with average
response times of 10 microseconds instead of the average 100
microseconds of other SSDs. Enterprise flash devices (EFDs) are
designed to handle the demands of tier-1 application with performance
and response times similar to less-expensive SSDs.
In traditional HDDs, a re-written file will generally occupy the same
location on the disk surface as the original file, whereas in SSDs the
new copy will often be written to different NAND cells for the purpose
of wear leveling. The wear-leveling algorithms are complex and
difficult to test exhaustively; as a result, one major cause of data
loss in SSDs is firmware bugs.
The following table shows a detailed overview of the advantages and
disadvantages of both technologies. Comparisons reflect typical
characteristics, and may not hold for a specific device.
Attribute or characteristic
Hard disk drive
If left without power, worn out SSDs typically start to lose data
after about one to two years in storage, depending on temperature. New
drives are supposed to retain data for about ten years. SSDs are
not suited for archival use.
If kept in a dry environment at low temperature, HDDs can retain their
data for a very long period of time even without power. However, the
mechanical parts tend to become clotted over time and the drive fails
to spin up after a few years in storage.
Almost instantaneous; no mechanical components to prepare. May need a
few milliseconds to come out of an automatic power-saving mode.
Drive spin-up may take several seconds. A system with many drives may
need to stagger spin-up to limit peak power drawn, which is briefly
high when an HDD is first started.
Random access time
Typically under 0.1 ms. As data can be retrieved directly from
various locations of the flash memory, access time is usually not a
big performance bottleneck.
Ranges from 2.9 (high end server drive) to 12 ms (laptop HDD) due
to the need to move the heads and wait for the data to rotate under
the read/write head.
Read latency time
Generally low because the data can be read directly from any location.
In applications where hard disk drive seeks are the limiting factor,
this results in faster boot and application launch times (see Amdahl's
Much higher than SSDs. Read time is different for every different
seek, since the location of the data and the location of the head are
Data transfer rate
SSD technology can deliver rather consistent read/write speed, but
when lots of individual smaller blocks are accessed, performance is
reduced. In consumer products the maximum transfer rate typically
ranges from about 200 MB/s to 2500 MB/s, depending on the
drive. Enterprise market offers devices with multi-gigabyte per second
Once the head is positioned, when reading or writing a continuous
track, a modern HDD can transfer data at about 200 MB/s. In
practice transfer speeds are many times lower due to constant seeking,
as files are read from various locations or they are fragmented. Data
transfer rate depends also upon rotational speed, which can range from
3,600 to 15,000 rpm and also upon the track (reading from
the outer tracks is faster).
Read performance does not change based on where data is stored on an
Unlike mechanical hard drives, current SSD technology suffers from a
performance degradation phenomenon called write amplification, where
the NAND cells show a measurable drop in performance, and will
continue degrading throughout the life of the SSD. A technique
called wear leveling is implemented to mitigate this effect, but due
to the nature of the NAND chips, the drive will inevitably degrade at
a noticeable rate.
If data from different areas of the platter must be accessed, as with
fragmented files, response times will be increased by the need to seek
Impacts of file system fragmentation
There is limited benefit to reading data sequentially (beyond typical
FS block sizes, say 4 KB), making fragmentation negligible for
Defragmentation would cause wear by making additional writes of
NAND flash cells, which have a limited cycle life.
However, even on SSDs there is a practical limit on how much
fragmentation certain file systems can sustain; once that limit is
reached, subsequent file allocations fail. Consequently,
defragmentation may still be necessary, although to a lesser
Some file systems, like NTFS, become fragmented over time if
frequently written; periodic defragmentation is required to maintain
optimum performance. This usually is not an issue in modern file
SSDs have no moving parts and therefore are basically silent, although
on some SSDs, high pitch noise from the high voltage generator (for
erasing blocks) may occur.
HDDs have moving parts (heads, actuator, and spindle motor) and make
characteristic sounds of whirring and clicking; noise levels vary
between models, but can be significant (while often much lower than
the sound from the cooling fans). Laptop hard drives are relatively
A research conducted by Facebook found a consistent failure rate at
temperatures between 30 and 40 °C. Failure rate rises when
operating at temperatures higher than 40 °C, further increase of
temperature may trigger thermal throttling around 70 °C,
resulting reduced runtime performance. Reliability of early SSDs
without thermal throttling are more affected by temperature, than
newer ones with thermal throttling. In practice, SSDs usually do
not require any special cooling and can tolerate higher temperatures
than HDDs. High-end enterprise models installed as add-on cards or
2.5-inch bay devices may ship with heat sinks to dissipate generated
heat, requiring certain volumes of airflow to operate.
Ambient temperatures above 35 °C (95 °F) can shorten the
life of a hard disk, and reliability will be compromised at drive
temperatures above 55 °C (131 °F). Fan cooling may be
required if temperatures would otherwise exceed these values. In
practice, modern HDDs may be used with no special arrangements for
Lowest operating temperature
SSDs can operate at −55 °C (−67 °F).
Most modern HDDs can operate at 0 °C (32 °F).
Highest altitude when operating
SSDs have no issues on this.
HDDs can operate safely at an altitude of at most 3,000 meters
(10,000 ft). HDDs will fail to operate at altitudes above 12,000
meters (40,000 ft). With the introduction of Nitrogen
Filled (sealed) HDDs, this is expected to be less of
Moving from a cold environment to a warmer environment
SSDs have no issues on this.
A certain amount of acclimation time is needed when moving HDDs from a
cold environment to a warmer environment prior to operating it;
otherwise, internal condensation will occur and operating it
immediately will result in damage to its internal components.
SSDs do not require a breather hole.
Most modern HDDs require a breather hole in order for it to function
Susceptibility to environmental factors
No moving parts, very resistant to shock, vibration, and movement.
Heads floating above rapidly rotating platters are susceptible to
shock, vibration, and movement.
Installation and mounting
Not sensitive to orientation, vibration, or shock. Usually no exposed
Circuitry may be exposed, and it must not be short-circuited by
conductive materials (such as the metal chassis of a computer). Should
be mounted to protect against vibration and shock. Some HDDs should
not be installed in a tilted position.
Susceptibility to magnetic fields
Low impact on flash memory, but an electromagnetic pulse will damage
any electrical system, especially integrated circuits.
In general, magnets or magnetic surges may result in data corruption
or mechanical damage to the drive internals. Drive's metal case
provides a low level of shielding to the magnetic
Weight and size
SSDs, essentially semiconductor memory devices mounted on a circuit
board, are small and lightweight. They often follow the same form
factors as HDDs (2.5-inch or 1.8-inch), but the enclosures are made
mostly of plastic.
HDDs are generally heavier than SSDs, as the enclosures are made
mostly of metal, and they contain heavy objects such as motors and
large magnets. 3.5-inch drives typically weigh around 700 grams.
Reliability and lifetime
SSDs have no moving parts to fail mechanically. Each block of a
flash-based SSD can only be erased (and therefore written) a limited
number of times before it fails. The controllers manage this
limitation so that drives can last for many years under normal
use. SSDs based on
DRAM do not have a limited
number of writes. However the failure of a controller can make a SSD
unusable. Reliability varies significantly across different SSD
manufacturers and models with return rates reaching 40% for specific
drives. As of 2011[update] leading SSDs have lower return rates
than mechanical drives. Many SSDs critically fail on power
outages; a December 2013 survey of many SSDs found that only some of
them are able to survive multiple power outages.[needs update?]
HDDs have moving parts, and are subject to potential mechanical
failures from the resulting wear and tear. The storage medium itself
(magnetic platter) does not essentially degrade from read and write
According to a study performed by
Carnegie Mellon University
Carnegie Mellon University for both
consumer and enterprise-grade HDDs, their average failure rate is 6
years, and life expectancy is 9–11 years. Leading SSDs have
overtaken HDDs for reliability, however the risk of a sudden,
catastrophic data loss can be lower for HDDs.
When stored offline (unpowered in shelf) in long term, the magnetic
medium of HDD retains data significantly longer than flash memory used
Secure writing limitations
NAND flash memory cannot be overwritten, but has to be rewritten to
previously erased blocks. If a software encryption program encrypts
data already on the SSD, the overwritten data is still unsecured,
unencrypted, and accessible (drive-based hardware encryption does not
have this problem). Also data cannot be securely erased by overwriting
the original file without special "Secure Erase" procedures built into
HDDs can overwrite data directly on the drive in any particular
sector. However, the drive's firmware may exchange damaged blocks with
spare areas, so bits and pieces may still be present. Some
manufacturers' HDDs fill the entire drive with zeroes, including
relocated sectors, on ATA Secure Erase Enhanced Erase command.
Price per capacity
SSDs generally are more expensive than HDDs and expected to remain so
into the next decade..
SSD price as of first quarter 2018 around 30 cents (US) per gigabyte
based on 4 TB models.
Prices have generally declined annually and as of 2018 are expected to
continue to do so.
HDD price as of first quarter 2018 around 2 to 3 cents (US) per
gigabyte based on 1 TB models.
Prices have generally declined annually and as of 2018 are expected to
continue to do so.
In 2016, SSDs were available in sizes up to 60 TB, but less
costly, 120 to 512 GB models were more common.
In 2016, HDDs of up to 14 TB were available.
Read/write performance symmetry
Less expensive SSDs typically have write speeds significantly lower
than their read speeds. Higher performing SSDs have similar read and
HDDs generally have slightly longer (worse) seek times for writing
than for reading.
Free block availability and TRIM
SSD write performance is significantly impacted by the availability of
free, programmable blocks. Previously written data blocks no longer in
use can be reclaimed by TRIM; however, even with TRIM, fewer free
blocks cause slower performance.
HDDs are not affected by free blocks and do not benefit from TRIM.
High performance flash-based SSDs generally require half to a third of
the power of HDDs. High-performance
DRAM SSDs generally require as
much power as HDDs, and must be connected to power even when the rest
of the system is shut down. Emerging technologies like
DevSlp can minimize power requirements of idle drives.
The lowest-power HDDs (1.8-inch size) can use as little as
0.35 watts when idle. 2.5-inch drives typically use 2 to 5
watts. The highest-performance 3.5-inch drives can use up to about 20
Maximum areal storage density (Terabits per square inch)
Main article: Memory card
CompactFlash card used as an SSD
While both memory cards and most SSDs use flash memory, they serve
very different markets and purposes. Each has a number of different
attributes which are optimized and adjusted to best meet the needs of
particular users. Some of these characteristics include power
consumption, performance, size, and reliability.
SSDs were originally designed for use in a computer system. The first
units were intended to replace or augment hard disk drives, so the
operating system recognized them as a hard drive. Originally, solid
state drives were even shaped and mounted in the computer like hard
drives. Later SSDs became smaller and more compact, eventually
developing their own unique form factors such as
M.2 form factor. The
SSD was designed to be installed permanently inside a computer.
In contrast, memory cards (such as
Secure Digital (SD), CompactFlash
(CF), and many others) were originally designed for digital cameras
and later found their way into cell phones, gaming devices, GPS units,
etc. Most memory cards are physically smaller than SSDs, and designed
to be inserted and removed repeatedly. There are adapters which
enable some memory cards to interface to a computer, allowing use as
an SSD, but they are not intended to be the primary storage device in
the computer. The typical
CompactFlash card interface is three to four
times slower than an SSD. As memory cards are not
designed to tolerate the amount of reading and writing which occurs
during typical computer use, their data may get damaged unless special
procedures are taken to reduce the wear on the card to a minimum.
SSDs have very different failure modes than traditional magnetic hard
drives. Because of their design, some kinds of failure are
inapplicable (motors cannot wear out or magnetic heads fail, because
these are not needed in an SSD). Instead, other kinds of failure are
possible (for example, incomplete or failed writes due to sudden power
failure can be more of a problem than with HDDs, and if a chip fails
then all the data on it is lost, a scenario not applicable to magnetic
drives). However on the whole statistics show that SSDs are generally
highly reliable, and often continue working far beyond the expected
lifetime as stated by their manufacturer.
SSD reliability and failure modes
An early test by
Techreport.com which ran for 18 months during 2013 -
2015 had previously tested a number of SSDs to destruction to identify
how and at what point they failed; the test found that "All of the
drives surpassed their official endurance specifications by writing
hundreds of terabytes without issue", described as being far beyond
any usual size for a "typical consumer". The first SSD to fail
was a TLC based drive - a type of design expected to be less durable
than either SLC or MLC - and the SSD concerned managed to write over
800,000 GB (800 TB or 0.8 petabytes) before failing; three SSDs in the
test managed to write almost three times that amount (almost 2.5 PB)
before they also failed. So the capability of even consumer SSDs
to be remarkably reliable was already established.
A 2016 study of "millions of drive days" in production use by SSDs
over a six year period, found that SSDs fail at a "significantly
lower" rate than HDDs, but have potential for localized data loss due
to unreadable blocks to be more of a problem than with HDDs. It came
to a number of "unexpected conclusions":
In the real world, MLC based designs - believed less reliable than SLC
designs - are often as reliable as SLC. (The findings state that "SLC
[is] not generally more reliable than MLC")
Device age, measured by days in use, is the main factor in SSD
reliability, and not amount of data read or written. Because this
finding persists after controlling for early failure and other
factors, it is likely that factors such as "silicon aging" is a cause
of this trend. The correlation is significant (around 0.2 - 0.4).
Raw bit error rates (RBER) grows much slower than usually believed and
is not exponential as often assumed, nor is it a good predictor of
other errors or SSD failure.
The uncorrectable bit error rate (UBER) is widely used but is not a
good predictor of failure either. However SSD UBER rates are higher
than those for HDDs, so although they do not predict failure, they can
lead to data loss due to unreadable blocks being more common on SSDs
than HDDs. The conclusion states that although more reliable overall,
the rate of uncorrectable errors able to impact a user is larger.
"Bad blocks in new SSDs are common, and drives with a large number of
bad blocks are much more likely to lose hundreds of other blocks, most
likely due to die or chip failure. 30-80 percent of SSDs develop at
least one bad block and 2-7 percent develop at least one bad chip in
the first four years of deployment."
There is no sharp increase in errors after the expected lifetime is
Most SSDs develop no more than a few bad blocks, perhaps 2 - 4. SSDs
that develop many bad blocks often go on to develop far more (perhaps
hundreds), and may be prone to failure. However most drives (99%+) are
shipped with bad blocks from manufacture. The finding overall was that
bad blocks are common and 30-80% of drives will develop at least one
in use, but even a few bad blocks (2 - 4) is a predictor of up to
hundreds of bad blocks at a later time. The bad block count at
manufacture correlates with later development of further bad blocks.
The report conclusion added that SSDs tended to either have "less than
a handful" of bad blocks or "a large number", and suggested that this
might be a basis for predicting eventual failure.
Around 2-7% of SSDs will develop bad chips in their first 4 years of
use. Over 2/3 of these chips will have breached their manufacturers'
tolerances and specifications, which typically guarantee that no more
than 2% of blocks on a chip will fail within its expected write
96% of those SSDs that need repair (warranty servicing), need repair
only once in their life. Days between repair vary from "a couple of
thousand days" to "nearly 15,000 days" depending on the model.
Data recovery and secure deletion
Solid state drives have set new challenges for data recovery
companies, as the way of storing data is non-linear and much more
complex than that of hard disk drives. The strategy the drive operates
by internally can largely vary between manufacturers, and the TRIM
command zeroes the whole range of a deleted file.
Wear leveling also
means that the physical address of the data and the address exposed to
the operating system are different.
As for secure deletion of data, ATA Secure Erase command could be
used. A program such as hdparm can be used for this purpose.
JEDEC Solid State Technology Association(JEDEC) has published
standards for reliability metrics:
Unrecoverable Bit Error Ratio (UBER)
Terabytes Written (TBW) - The number of terabytes that can be written
to a drive within it's warranty.
Drive Writes Per Day (DWPD) - The number of times the total capacity
of the drive may be written to per day within its warranty.
Until 2009[why?], SSDs were mainly used in those aspects of mission
critical applications where the speed of the storage system needed to
be as high as possible. Since flash memory has become a common
component of SSDs, the falling prices and increased densities have
made it more cost-effective for many other applications. Organizations
that can benefit from faster access of system data include equity
trading companies, telecommunication corporations, and streaming media
and video editing firms. The list of applications which could benefit
from faster storage is vast.
Flash-based solid-state drives can be used to create network
appliances from general-purpose personal computer hardware. A write
protected flash drive containing the operating system and application
software can substitute for larger, less reliable disk drives or
CD-ROMs. Appliances built this way can provide an inexpensive
alternative to expensive router and firewall hardware.[citation
SSDs based on an
SD card with a live SD operating system are easily
write-locked. Combined with a cloud computing environment or other
writable medium, to maintain persistence, an OS booted from a
SD card is robust, rugged, reliable, and impervious to
permanent corruption. If the running OS degrades, simply turning the
machine off and then on returns it back to its initial uncorrupted
state and thus is particularly solid. The
SD card installed OS does
not require removal of corrupted components since it was write-locked
though any written media may need to be restored.
Hard drives caching
Intel introduced a caching mechanism for their
(and mobile derivatives) called Smart Response Technology, which
SATA SSD to be used as a cache (configurable as write-through
or write-back) for a conventional, magnetic hard disk drive. A
similar technology is available on HighPoint's RocketHybrid PCIe
Solid-state hybrid drives (SSHDs) are based on the same principle, but
integrate some amount of flash memory on board of a conventional drive
instead of using a separate SSD. The flash layer in these drives can
be accessed independently from the magnetic storage by the host using
ATA-8 commands, allowing the operating system to manage it. For
example, Microsoft's ReadyDrive technology explicitly stores portions
of the hibernation file in the cache of these drives when the system
hibernates, making the subsequent resume faster.
Dual-drive hybrid systems are combining the usage of separate SSD and
HDD devices installed in the same computer, with overall performance
optimization managed by the computer user, or by the computer's
operating system software. Examples of this type of system are bcache
and dm-cache on Linux, and Apple’s Fusion Drive.
File system support for SSDs
File systems optimized for flash memory, solid state
Typically the same file systems used on hard disk drives can also be
used on solid state drives. It is usually expected for the file system
to support the
TRIM command which helps the SSD to recycle discarded
data (support for
TRIM arrived some years after SSDs themselves but is
now nearly universal). This means that file system does not need to
manage wear leveling or other flash memory characteristics, as they
are handled internally by the SSD. Some flash file systems using
log-based designs (F2FS, JFFS2) help to reduce write amplification on
SSDs, especially in situations where only very small amounts of data
are changed, such as when updating file system metadata.
While not a file system feature, operating systems should also aim to
align partitions correctly, which avoids excessive read-modify-write
cycles. A typical practice for personal computers is to have each
partition aligned to start at a 1 MB (= 1,048,576 bytes) mark,
which covers all common SSD page and block size scenarios, as it is
divisible by all commonly used sizes - 1 MB, 512 KB,
128 KB, 4 KB, and 512 bytes. Modern operating system
installation software and disk tools handle this automatically.
The ext4, Btrfs, XFS, JFS, and
F2FS file systems include support for
the discard (
TRIM or UNMAP) function. As of November 2013, ext4 can be
recommended as a safe choice.
F2FS is a modern file system optimized
for flash-based storage, and from a technical perspective is a very
good choice, but is still in experimental stage.
Kernel support for the
TRIM operation was introduced in version 2.6.33
Linux kernel mainline, released on 24 February 2010. To
make use of it, a filesystem must be mounted using the discard
Linux swap partitions are by default performing discard
operations when the underlying drive supports TRIM, with the
possibility to turn them off, or to select between one-time or
continuous discard operations. Support for queued TRIM,
which is a SATA 3.1 feature that results in
TRIM commands not
disrupting the command queues, was introduced in
Linux kernel 3.12,
released on November 2, 2013.
An alternative to the kernel-level
TRIM operation is to use a
user-space utility called fstrim that goes through all of the unused
blocks in a filesystem and dispatches
TRIM commands for those areas.
fstrim utility is usually run by cron as a scheduled task. As of
November 2013[update], it is used by the Ubuntu Linux
distribution, in which it is enabled only for
Intel and Samsung
solid-state drives for reliability reasons; vendor check can be
disabled by editing file /etc/cron.weekly/fstrim using instructions
contained within the file itself.
Since 2010, standard
Linux drive utilities have taken care of
appropriate partition alignment by default.
Linux performance considerations
An SSD that uses
NVM Express as the logical device interface, in form
of a PCI Express 3.0 ×4 expansion card
Linux distributions usually do not configure the
installed system to use
TRIM and thus the /etc/fstab file requires
manual modifications. This is because of the notion that the
TRIM command implementation might not be optimal.
It has been proven to cause a performance degradation instead of a
performance increase under certain circumstances. As of
Linux sends an individual
TRIM command to
each sector, instead of a vectorized list defining a
TRIM range as
recommended by the
TRIM specification. This deficiency has
existed for years and there are no known plans to eliminate it.
For performance reasons, it is recommended to switch the I/O scheduler
from the default
CFQ (Completely Fair Queuing) to NOOP or Deadline.
CFQ was designed for traditional magnetic media and seek
optimizations, thus many of those I/O scheduling efforts are wasted
when used with SSDs. As part of their designs, SSDs are offering much
bigger levels of parallelism for I/O operations, so it is preferable
to leave scheduling decisions to their internal logic –
especially for high-end SSDs.
A scalable block layer for high-performance SSD storage, known as
blk-multiqueue or blk-mq and developed primarily by Fusion-io
engineers, was merged into the
Linux kernel mainline in kernel version
3.13, released on 19 January 2014. This leverages the performance
offered by SSDs and NVM Express, by allowing much higher I/O
submission rates. With this new design of the
Linux kernel block
layer, internal queues are split into two levels (per-CPU and
hardware-submission queues), thus removing bottlenecks and allowing
much higher levels of I/O parallelization. As of version 4.0 of the
Linux kernel, released on 12 April 2015,
VirtIO block driver, the SCSI
layer (which is used by
Serial ATA drivers), device mapper framework,
loop device driver, unsorted block images (UBI) driver (which
implements erase block management layer for flash memory devices) and
RBD driver (which exports Ceph RADOS objects as block devices) have
been modified to actually use this new interface; other drivers will
be ported in the following releases.
OS X versions since 10.6.8 (Snow Leopard) support
TRIM but only
when used with an Apple-purchased SSD.
TRIM is not automatically
enabled for third-party drives, although it can be enabled by using
third-party utilities such as Trim Enabler. The status of
TRIM can be
checked in the System Information application or in the
system_profiler command-line tool.
OS X version 10.11 (El Capitan) and 10.10.4 (Yosemite) include
sudo trimforce enable as a Terminal command that enables
non-Apple SSDs. There is also a technique to enable
versions of OS X earlier than 10.6.8, although it remains
TRIM is actually utilized properly in those
Microsoft Windows prior to 7 do not take any special
measures to support solid state drives. Starting from Windows 7, the
NTFS file system provides
TRIM support (other file systems on
Windows do not support TRIM).
By default, Windows 7 and newer versions execute
automatically if the device is detected to be a solid-state drive. To
change this behavior, in the Registry key
HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlFileSystem the value
DisableDeleteNotification can be set to 1 to prevent the mass storage
driver from issuing the
TRIM command. This can be useful in situations
where data recovery is preferred over wear leveling (in most cases,
TRIM irreversibly resets all freed space).
TRIM command for more than just file delete
TRIM operation is fully integrated with partition- and
volume-level commands like format and delete, with file system
commands relating to truncate and compression, and with the System
Restore (also known as Volume Snapshot) feature.
Windows 7 and later
Windows 7 and later versions have native support for
SSDs. The operating system detects the presence of an SSD
and optimizes operation accordingly. For SSD devices Windows disables
SuperFetch and ReadyBoost, boot-time and application prefetching
operations. Despite the initial statement by Steven
Sinofsky prior to the release of Windows 7, however,
defragmentation is not disabled, even though its behavior on SSDs
differs. One reason is the low performance of Volume Shadow Copy
Service on fragmented SSDs. The second reason is to avoid
reaching the practical maximum number of file fragments that a volume
can handle. If this maximum is reached, subsequent attempts to write
to the drive will fail with an error message.
Windows 7 also includes support for the
TRIM command to reduce garbage
collection for data which the operating system has already determined
is no longer valid. Without support for TRIM, the SSD would be unaware
of this data being invalid and would unnecessarily continue to rewrite
it during garbage collection causing further wear on the SSD. It is
beneficial to make some changes that prevent SSDs from being treated
more like HDDs, for example cancelling defragmentation, not filling
them to more than about 75% of capacity, not storing frequently
written-to files such as log and temporary files on them if a hard
drive is available, and enabling the
Windows Vista generally expects hard disk drives rather than
Windows Vista includes
ReadyBoost to exploit
characteristics of USB-connected flash devices, but for SSDs it only
improves the default partition alignment to prevent read-modify-write
operations that reduce the speed of SSDs. Most SSDs are typically
split into 4 kB sectors, while most systems are based on
512 byte sectors with their default partition setups unaligned to
the 4 KB boundaries. The proper alignment does not help the
SSD's endurance over the life of the drive; however, some Vista
operations, if not disabled, can shorten the life of the SSD.
Drive defragmentation should be disabled because the location of the
file components on an SSD doesn't significantly impact its
performance, but moving the files to make them contiguous using the
Windows Defrag routine will cause unnecessary write wear on the
limited number of P/E cycles on the SSD. The Superfetch feature will
not materially improve the performance of the system and causes
additional overhead in the system and SSD, although it does not cause
Windows Vista does not send the
TRIM command to solid state
drives, but some third part utilities such as SSD Doctor will
periodically scan the drive and
TRIM the appropriate entries.
Solaris as of version 10 Update 6 (released in October 2008), and
recent versions of OpenSolaris, Solaris Express Community Edition,
ZFS on Linux, and
FreeBSD all can use SSDs as a
performance booster for ZFS. A low-latency SSD can be used for the ZFS
Intent Log (ZIL), where it is named the SLOG. This is used every time
a synchronous write to the drive occurs. An SSD (not necessarily with
a low-latency) may also be used for the level 2 Adaptive Replacement
Cache (L2ARC), which is used to cache data for reading. When used
either alone or in combination, large increases in performance are
FreeBSD introduced support for
TRIM on September 23,
2012. The code builds a map of regions of data that were freed;
on every write the code consults the map and eventually removes ranges
that were freed before, but are now overwritten. There is a
low-priority thread that TRIMs ranges when the time comes.
Also the Unix
File System (UFS) supports the
According to Microsoft's former Windows division president Steven
Sinofsky, "there are few files better than the pagefile to place on an
SSD". According to collected telemetry data,
Microsoft had found
the pagefile.sys to be an ideal match for SSD storage.
Linux swap partitions are by default performing
TRIM operations when
the underlying block device supports TRIM, with the possibility to
turn them off, or to select between one-time or continuous TRIM
If an operating system does not support using
TRIM on discrete swap
partitions, it might be possible to use swap files inside an ordinary
file system instead. For example, OS X does not support swap
partitions; it only swaps to files within a file system, so it can use
TRIM when, for example, swap files are deleted.
DragonFly BSD allows SSD-configured swap to also be used as file
system cache. This can be used to boost performance on both
desktop and server workloads. The bcache, dm-cache, and Flashcache
projects provide a similar concept for the
The following are noted standardization organizations and bodies that
work to create standards for solid-state drives (and other computer
storage devices). The table below also includes organizations which
promote the use of solid-state drives. This is not necessarily an
Organization or Committee
Coordinates technical standards activity between ANSI in the USA and
joint ISO/IEC committees worldwide
Develops open standards and publications for the microelectronics
Focuses on solid-state drive standards and publications
Provides standard software and hardware programming interfaces for
nonvolatile memory subsystems
Provides the industry with guidance and support for implementing the
Works on storage industry standards needing attention when not
addressed by other standards committees
Develops and promotes standards, technologies, and educational
services in the management of information
Fosters the growth and success of solid state storage
Solid-state drive technology has been marketed to the military and
niche industrial markets since the mid-1990s.
Along with the emerging enterprise market, SSDs have been appearing in
ultra-mobile PCs and a few lightweight laptop systems, adding
significantly to the price of the laptop, depending on the capacity,
form factor and transfer speeds. For low-end applications, a
drive may be obtainable for anywhere from $10 to $100 or so, depending
on capacity and speed; alternatively, a
CompactFlash card may be
paired with a CF-to-IDE or CF-to-
SATA converter at a similar cost.
Either of these requires that write-cycle endurance issues be managed,
either by refraining from storing frequently written files on the
drive or by using a flash file system. Standard
usually have write speeds of 7 to 15 MB/s while the more
expensive upmarket cards claim speeds of up to 60 MB/s.
One of the first mainstream releases of SSD was the XO Laptop, built
as part of the
One Laptop Per Child
One Laptop Per Child project. Mass production of these
computers, built for children in developing countries, began in
December 2007. These machines use 1,024
NAND flash as
primary storage which is considered more suitable for the harsher than
normal conditions in which they are expected to be used.
shipping ultra-portable laptops with
SanDisk SSDs on April 26,
Asus released the Eee PC subnotebook on October 16, 2007,
with 2, 4 or 8 gigabytes of flash memory. On January 31, 2008,
Apple released the MacBook Air, a thin laptop with an optional
64 GB SSD. The Apple Store cost was $999 more for this option, as
compared with that of an 80 GB 4200 RPM hard disk
drive. Another option, the
ThinkPad X300 with a
64 gigabyte SSD, was announced by
Lenovo in February 2008.
On August 26, 2008,
ThinkPad X301 with 128 GB SSD
option which adds approximately $200 US.
Some Mtron solid-state drives
In 2008, low-end netbooks appeared with SSDs. In 2009, SSDs began to
appear in laptops.
On January 14, 2008,
EMC Corporation (EMC) became the first enterprise
storage vendor to ship flash-based SSDs into its product portfolio
when it announced it had selected STEC, Inc.'s Zeus-
IOPS SSDs for its
Symmetrix DMX systems. In 2008, Sun released the Sun Storage 7000
Unified Storage Systems (codenamed Amber Road), which use both solid
state drives and conventional hard drives to take advantage of the
speed offered by SSDs and the economy and capacity offered by
Dell began to offer optional 256 GB solid state drives on select
notebook models in January 2009. In May 2009, Toshiba
launched a laptop with a 512 GB SSD.
Since October 2010, Apple's
MacBook Air line has used a solid state
drive as standard. In December 2010,
OCZ RevoDrive X2
was available in 100 GB to 960 GB capacities delivering
speeds over 740 MB/s sequential speeds and random small file
writes up to 120,000 IOPS. In November 2010, Fusion-io
released its highest performing SSD drive named ioDrive Octal
utilising PCI-Express x16 Gen 2.0 interface with storage space of
5.12 TB, read speed of 6.0 GB/s, write speed of
4.4 GB/s and a low latency of 30 microseconds. It has
1.19 M Read 512 byte
IOPS and 1.18 M Write 512 byte
In 2011, computers based on Intel's
Ultrabook specifications became
available. These specifications dictate that Ultrabooks use an SSD.
These are consumer-level devices (unlike many previous flash offerings
aimed at enterprise users), and represent the first widely available
consumer computers using SSDs aside from the MacBook Air. At CES
OCZ Technology demonstrated the R4 CloudServ
PCIe SSDs capable
of reaching transfer speeds of 6.5 GB/s and 1.4 million
IOPS. Also announced was the Z-Drive R5 which is available in
capacities up to 12 TB, capable of reaching transfer speeds of
7.2 GB/s and 2.52 million
IOPS using the
PCI Express x16 Gen
In December 2013, Samsung introduced and launched the industry's first
1 TB m
SATA SSD. In August 2015, Samsung announced a
16 TB SSD, at the time the world's highest-capacity single
storage device of any type.
Quality and performance
Main article: Disk drive performance characteristics
In general, performance of any particular device can vary
significantly in different operating conditions. For example, the
number of parallel threads accessing the storage device, the I/O block
size, and the amount of free space remaining can all dramatically
change the performance (i.e. transfer rates) of the device.
SSD technology has been developing rapidly. Most of the performance
measurements used on disk drives with rotating media are also used on
SSDs. Performance of flash-based SSDs is difficult to benchmark
because of the wide range of possible conditions. In a test performed
in 2010 by Xssist, using IOmeter, 4 kB random 70% read/30% write,
queue depth 4, the
IOPS delivered by the
Intel X25-E 64 GB G1
started around 10,000 IOPs, and dropped sharply after
8 minutes to 4,000 IOPS, and continued to decrease gradually
for the next 42 minutes.
IOPS vary between 3,000 and 4,000 from
around 50 minutes onwards for the rest of the 8+ hour test
Write amplification is the major reason for the change in performance
of an SSD over time. Designers of enterprise-grade drives try to avoid
this performance variation by increasing over-provisioning, and by
employing wear-leveling algorithms that move data only when the drives
are not heavily utilized.
SSD shipments were 11 million units in 2009, 17.3 million units
in 2011 for a total of US$5 billion, 39 million units in
2012, and are expected to rise to 83 million units in 2013 to
201.4 million units in 2016 and to 227 million units in
Revenues for the SSD market (including low-cost PC solutions)
worldwide totalled $585 million in 2008, rising over 100% from $259
million in 2007.
Information Technology portal
Board solid-state drive
List of solid-state drive manufacturers
^ a b "What is a Solid State Disk?". Ramsan.com. Texas Memory Systems.
Archived from the original on 4 February 2008.
^ Whittaker, Zack. "Solid-state disk prices falling, still more costly
than hard disks". Between the Lines. ZDNet. Archived from the original
on 2 December 2012. Retrieved 14 December 2012.
^ "What is solid state disk? - A Word Definition From the Webopedia
Computer Dictionary". Webopedia. ITBusinessEdge. Archived from the
original on 3 December 2012. Retrieved 14 December 2012.
^ a b c d e f "Solid State Storage 101: An introduction to Solid State
Storage" (PDF). SNIA. January 2009. Archived from the original (PDF)
on February 6, 2009. Retrieved 9 August 2010.
^ STEC."SSD Power Savings Render Significant Reduction to TCO Archived
2010-11-06 at WebCite." Retrieved October 25, 2010.
^ a b Vamsee Kasavajhala (May 2011). "SSD vs HDD Price and Performance
Dell technical white paper" (PDF).
Dell PowerVault Technical
Marketing. Archived (PDF) from the original on 12 May 2012. Retrieved
15 June 2012.
^ "Archived copy". Archived from the original on 2017-03-18. Retrieved
^ "WD shows off its first hybrid drive, the WD Black SSHD". Cnet.
Archived from the original on 29 March 2013. Retrieved 26 March
^ Patrick Schmid and Achim Roos (2012-02-08). "Momentus XT 750 GB
Review: A Second-Gen Hybrid Hard Drive". Retrieved 2013-11-07.
^ Anand Lal Shimpi (2011-12-13). "Seagate 2nd Generation Momentus XT
(750GB) Hybrid HDD Review". Archived from the original on 2013-11-01.
^ "StorageTek - circa 2004". storagesearch.com. Retrieved December 11,
^ "Dataram Corp: 1977 Annual Report" (PDF). Archived (PDF) from the
original on 2011-09-27. Retrieved 2011-06-19.
^ "HISTORY OF THE SANDISK BRAND. 1991 News". sandisk.com. SanDisk
Corp. 1991. Retrieved December 12, 2017.
^ Mellor, Chris. "There's a lot of sizzle with this STEC".
theregister.co.uk. Archived from the original on 11 November 2013.
Retrieved 24 November 2014.
^ Odagiri, Hiroyuki; Goto, Akira; Sunami, Atsushi; Nelson, Richard R.
(2010). Intellectual Property Rights, Development, and Catch Up: An
International Comparative Study. Oxford University Press.
pp. 224–227. ISBN 0-19-957475-8.
^ Drossel, Gary (February 2007). "Solid-state drives meet military
storage security requirements" (PDF). Military Embedded Systems.
Archived (PDF) from the original on 2011-07-14. Retrieved
^ "BiTMICRO 1999 News Releases". BiTMICRO. 1999. Archived from the
original on 2010-05-01. Retrieved 2010-06-13.
Fusion-io announces ioDrive, placing the power of a SAN in the palm
of your hand" (PDF). Fusion-io. 2007-09-25. Archived from the original
(PDF) on 2010-05-09. Retrieved 2010-06-13.
^ "OCZ's New Blazing Fast 1TB Z SSD Drive". Tom's Hardware.
2009-03-04. Retrieved 2009-10-21.
^ Jansen, Ng (2009-12-02). "Micron Announces World's First Native
SATA Solid State Drive". DailyTech. Archived from the original
on 2009-12-05. Retrieved 2009-12-02.
^ Mellor, Chris. "EMC has changed enterprise disk storage for
ever:First into the enterprise flash breech". Techworld. Archived from
the original on 2010-07-15. Retrieved 2010-06-12.
^ Burke, Barry A. (2009-02-18). "1.040: efd - what's in a name?". The
Storage Anarchist. Archived from the original on 2010-06-12. Retrieved
^ Anand Lal Shimpi (2012-11-09). "The
Intel SSD DC S3700 (200GB)
Review?". AnandTech. Archived from the original on 2014-10-25.
^ "PX02SSB080 / PX02SSF040 / PX02SSF020 / PX02SSF010". Toshiba
Corporation. Archived from the original on 2016-02-15.
^ Rent, Thomas M. (2010-04-09). "SSD Controller Detail".
StorageReview.com. Archived from the original on 2010-10-15.
^ Bechtolsheim, Andy (2008). "The Solid State Storage Revolution"
(PDF). SNIA.org. Retrieved 2010-11-07.
^ a b Werner, Jeremy (2010-08-17). "A Look Under the Hood at Some
Unique SSD Features" (PDF). SandForce.com. Archived (PDF) from the
original on 2011-12-06. Retrieved 2012-08-28.
^ a b c "The SSD Anthology: Understanding SSDs and New Drives from
OCZ". AnandTech.com. 2009-03-18. Archived from the original on
^ "Flash SSD with 250 MB/s writing speed". Micron.com. Archived
from the original on 2009-06-26. Retrieved 2009-10-21.
^ Shimpi, Anand Lal (2011-02-24). "
OCZ Vertex 3 Preview: Faster and
Cheaper than the Vertex 3 Pro". Anandtech.com. Archived from the
original on 2011-05-29. Retrieved 2011-06-30.
^ Shimpi, Anand Lal (31 December 2009). "OCZ's Vertex 2 Pro Preview:
The Fastest MLC SSD We've Ever Tested". AnandTech. Archived from the
original on 12 May 2013. Retrieved 16 June 2013.
^ SLC and MLC Archived 2013-04-05 at the Wayback Machine. SSD
Festplatten. Retrieved 2013-04-10.
^ "The Top 20 Things to Know About SSD" (PDF). seagate.com. 2011.
Archived (PDF) from the original on 2016-05-27. Retrieved
^ a b Mittal et al., "A Survey of Software Techniques for Using
Non-Volatile Memories for Storage and Main Memory Systems Archived
2015-09-19 at the Wayback Machine.", IEEE TPDS, 2015
^ Lai, Eric (2008-11-07). "SSD laptop drives 'slower than hard
disks'". Computerworld. Archived from the original on 2011-06-29.
^ Mearian, Lucas (2008-08-27). "Solid-state disk lackluster for
laptops, PCs". Computerworld.com. Archived from the original on
2016-10-23. Retrieved 2017-05-06.
^ a b "Are MLC SSDs Ever Safe in Enterprise Apps?". Storagesearch.com.
ACSL. Archived from the original on 2008-09-19.
^ Lucchesi, Ray (September 2008). "SSD flash drives enter the
enterprise" (PDF). Silverton Consulting. Archived (PDF) from the
original on 2015-12-10. Retrieved 2010-06-18.
^ Bagley, Jim (2009-07-01). "Over-provisioning: a winning strategy or
a retreat?" (PDF). StorageStrategies Now. p. 2. Archived from the
original (PDF) on 2010-01-04. Retrieved 2010-06-19.
^ Drossel, Gary (2009-09-14). "Methodologies for Calculating SSD
Useable Life" (PDF). Storage Developer Conference, 2009. Archived
(PDF) from the original on 2015-12-08. Retrieved 2010-06-20.
^ Cash, Kelly. "Flash SSDs - Inferior Technology or Closet
Superstar?". BiTMICRO. Archived from the original on 2011-07-19.
^ Kerekes, Zsolt. "RAM SSDs". storagesearch.com. ACSL. Archived from
the original on 22 August 2010. Retrieved 14 August 2010.
^ Lloyd, Chris. "Next-gen storage that makes SSD look slow Using RAM
drives for ultimate performance". techradar.com. Archived from the
original on 4 December 2014. Retrieved 27 November 2014.
^ Allyn Malventano. "CES 2012:
OCZ shows DDR based
aeonDrive" Archived 2013-07-19 at the Wayback Machine.. 2012.
^ "RIndMA Disk". Hardwareforall.com. Archived from the original on
2010-01-04. Retrieved 2010-08-13.
^ Kerekes, Zsolt (2007). "Flash SSD vs RAM SSD Prices".
StorageSearch.com. ACSL. Archived from the original on
^ "Why Are SSDs Still So Expensive?". aGigaTech.com. 12 December 2009.
Archived from the original on 3 November 2012.
^ Jim Handy. "Viking: Why Wait for Nonvolatile DRAM?" Archived
2013-06-24 at the Wayback Machine.. 2013.
^ "Hybrid DIMMs And The Quest For Speed". Network Computing. Archived
from the original on 20 December 2014. Retrieved 20 December
^ The SSD Guy (2013-03-30). "Seagate Upgrades Hybrids, Phases Out
7,200RPM HDDs". The SSD Guy. Archived from the original on 2013-12-16.
^ "Hybrid Storage Drives". Archived from the original on
^ Douglas Perry. "Buffalo Shows SSDs with MRAM Cache" Archived
2013-12-16 at the Wayback Machine.. 2012.
^ Rick Burgess. "Everspin first to ship ST-MRAM, claims 500x faster
than SSDs" Archived 2013-04-03 at the Wayback Machine.. 2012.
^ "Intel, Micron reveal Xpoint, a new memory architecture that could
outclass DDR4 and NAND - ExtremeTech". ExtremeTech. Archived from the
original on 2015-08-20.
^ a b Smith, Ryan (18 August 2015). "
Intel Announces Optane Storage
3D XPoint Products". Archived from the original on 19 August
2015. products will be available in 2016, in both standard SSD (PCIe)
form factors for everything from Ultrabooks to servers, and in a DIMM
form factor for Xeon systems for even greater bandwidth and lower
latencies. As expected,
Intel will be providing storage controllers
optimized for the
3D XPoint memory
^ "Intel, Micron debut
3D XPoint storage technology that's 1,000 times
faster than current SSDs". CNET. CBS Interactive. Archived from the
original on 2015-07-29.
^ "3D Xpoint memory: Faster-than-flash storage unveiled". BBC News.
Archived from the original on 2015-07-30.
^ Stephen Lawson (28 July 2015). "
Intel and Micron unveil
3D XPoint --
a new class of memory". Computerworld. Archived from the original on
30 July 2015.
^ "<--none-->". 2015-07-28. Intel's Rob Crooke explained, 'You
could put the cost somewhere between NAND and DRAM.'
^ a b Demerjian, Charlie (2010-05-03). "
SandForce SSDs break TPC-C
records". SemiAccurate.com. Archived from the original on 2010-11-27.
^ Arnd Bergmann (2011-02-18). "Optimizing
Linux with cheap flash
drives". LWN.net. Archived from the original on 2013-10-07. Retrieved
^ Jonathan Corbet (2007-05-15). "LogFS". LWN.net. Archived from the
original on 2013-10-04. Retrieved 2013-10-03.
^ Kerekes, Zsolt. "Surviving SSD sudden power loss".
storagesearch.com. Archived from the original on 22 November 2014.
Retrieved 28 November 2014.
Intel SSD, now off the sh..err, shamed list". Archived from the
original on February 3, 2012.
^ "Crucial's M500 SSD reviewed". Archived from the original on
^ "More Power-Loss Data Protection with
Intel SSD 320 Series" (PDF).
Intel. 2011. Archived from the original (PDF) on 2014-02-07. Retrieved
Intel Solid-State Drive 710: Endurance. Performance. Protection".
Archived from the original on 2012-04-06.
^ Anand Lal Shimpi (2012-11-09). "The
Intel SSD DC S3700 (200GB)
Review". AnandTech. Archived from the original on 2014-09-23.
^ Paul Alcorn. "Huawei Tecal ES3000
PCIe Enterprise SSD Internals".
Tom's IT Pro. Archived from the original on 2015-06-19.
^ "Serial Attached
SCSI Master Roadmap".
SCSI Trade Association.
2015-10-14. Archived from the original on 2016-03-07. Retrieved
^ "SATA-IO Releases
SATA Revision 3.0 Specification" (PDF) (Press
Serial ATA International Organization. May 27, 2009.
Archived (PDF) from the original on 11 June 2009. Retrieved 3 July
PCI Express 3.0 Frequently Asked Questions". pcisig.com. PCI-SIG.
Archived from the original on 2014-02-01. Retrieved 2014-05-01.
USB 10 Gbps - Ready for Development". Rock Hill
Herald. Archived from the original on 11 October 2014. Retrieved
^ "PATA SSD". Transcend. Archived from the original on
^ "Netbook SSDs". Super Talent. Archived from the original on
^ Kerekes, Zsolt (July 2010). "The (parallel)
SCSI SSD market".
StorageSearch.com. ACSL. Archived from the original on 2011-05-27.
^ Kristian, Vättö. "Apple Is Now Using
SanDisk SSDs in the Retina
MacBook Pro As Well". anandtech.com. Archived from the original on 29
November 2014. Retrieved 27 November 2014.
^ Ruth, Gene (2010-01-27). "SSD: Dump the hard disk form factor".
Burton Group. Archived from the original on 2010-02-09. Retrieved
^ Kerekes, Zsolt. "SSD Buyers Guide". StorageSearch.com. ACSL.
Archived from the original on 2010-06-14. Retrieved 2010-06-13.
M.2 Card". The
Serial ATA International Organization. Archived
from the original on 2013-10-03. Retrieved 2013-09-14.
^ Hachman, Mark. "SSD prices face uncertain future in 2014".
pcworld.com. Archived from the original on 2 December 2014. Retrieved
24 November 2014.
^ Beard, Brian (2009). "SSD Moving into the Mainstream as PCs Go 100%
Solid State" (PDF). Samsung Semiconductor, Inc. Archived (PDF) from
the original on 2011-07-16. Retrieved 2010-06-13.
^ "Enterprise SATADIMM". Viking Technology. Archived from the original
on 2011-11-04. Retrieved 2010-11-07.
^ "SATADOM". Innodisk. Archived from the original on 2011-07-07.
^ Pop, Sebastian. "
PCI Express SSD from
Fusion-io ioXtreme Is Aimed at
the Consumer Market". Softpedia. Archived from the original on 16 July
2011. Retrieved 9 August 2010.
^ Pariseau, Beth (16 March 2010). "LSI delivers Flash-based
with 6 Gbit/s SAS interface". Archived from the original on 6
November 2010. Retrieved 9 August 2010.
^ Kerekes, Zsolt. "SSDs". StorageSearch.com. ACSL. Archived from the
original on 27 May 2011. Retrieved 27 June 2011.
^ "New From SST: SST85LD0128 NANDrive - Single Package Flash Based
128MB Solid State Hard Disk Drive with ATA / IDE Interface". Memec
Newsletter. Dec 2006. Retrieved 27 June 2011.
^ "SST announces small ATA solid-state storage devices". Computer
Technology Review. 26 Oct 2006. Archived from the original on 1
October 2011. Retrieved 27 June 2011.
^ "M1000 Specifications". Memoright. Archived from the original on
2011-11-25. Retrieved 2011-07-07.
^ Chung, Yuping (19 Nov 2008). "Compact, shock- and error-tolerant
SSDs offer auto infotainment storage options". EE Times. Archived from
the original on 17 May 2012. Retrieved 27 June 2011.
^ "Benchmarking Enterprise SSDs" (PDF). Archived (PDF) from the
original on 2012-05-07. Retrieved 2012-05-06.
^ "SSD vs HDD - Why Solid State Drive". SSD Guide.
Archived from the original on 10 May 2013. Retrieved 17 June
^ "Price Comparison SSDs" (PDF). Archived (PDF) from the original on
2012-05-12. Retrieved 2012-05-06.
^ a b c BeHardware reported lower retailer return rates for SSDs than
HDDs between April and October 2010. Prieur, Marc (6 May 2011).
"Components returns rates". BeHardware. Archived from the original on
14 February 2012. Retrieved 10 February 2012.
^ A 2011 study by
Intel on the use of 45,000 SSDs reported an
annualized failure rate of 0.61% for SSDs, compared with 4.85% for
HDDs. "Validating the Reliability of Intel® Solid-State Drives".
Intel. July 2011. Archived from the original on 18 January 2012.
Retrieved 10 February 2012.
^ a b Prieur, Marc (16 November 2012). "Components returns rates (7)".
BeHardware. Archived from the original on 9 August 2013. Retrieved 25
^ Harris, Robin (2013-03-01). "How SSD power faults scramble your
data". ZDNet. CBS Interactive. Archived from the original on
^ Paul, Ian (14 January 2014). "Three-year, 27,000 drive study reveals
the most reliable hard drive makers". PC World. Archived from the
original on 15 May 2014. Retrieved 17 May 2014.
^ Schoeb, Leah (January 2013). "Should you believe vendors'
jaw-dropping solid-state performance specs?". Storage Magazine.
Archived from the original on 9 April 2013. Retrieved 1 April
^ Mearian, Lucas (3 August 2009). "
Intel confirms data corruption bug
in new SSDs, halts shipments". ComputerWorld. Archived from the
original on 25 January 2013. Retrieved 17 June 2013.
^ "More hard drive firmware bugs cause data loss". Defcon-5.com. 5
September 2009. Archived from the original on 18 May 2014. Retrieved
17 June 2013.
^ "Archived copy". Archived from the original on 2017-03-18. Retrieved
^ a b "HDD vs. SSD". diffen.com. Archived from the original on 5
December 2014. Retrieved 29 November 2014.
^ Markoff, John (2008-12-11). "Computing Without a Whirring Drive".
The New York Times. p. B9. Archived from the original on
2017-03-12. Using a standard Macintosh performance measurement utility
called Xbench, the
Intel solid-state drive increased the computer's
overall performance by almost half. Drive performance increased
^ "HP Solid State Drives (SSDs) for Workstations".
^ "Hard Drive Data Recovery Glossary". New York Data Recovery.
^ Radding, Alan. "
Solid-state storage finds its niche".
StorageSearch.com. ACSL. Archived from the original on 2008-01-03.
Retrieved 2007-12-29. Registration required.
^ a b Meyev, Aleksey (2008-04-23). "SSD, i-RAM and Traditional Hard
Disk drives". X-bit labs. Archived from the original on
^ "The PC Guide: Spindle Speed". Archived from the original on
^ "Super Talent SSD: 16GB of Solid State Goodness". AnandTech.
2007-05-07. Archived from the original on 2009-06-26. Retrieved
^ Rouse, Margaret Rouse. "write amplification".
searchsolidstatestorage. Archived from the original on 6 December
2014. Retrieved 29 November 2014.
^ "The Effects of Disk Fragmentation on System Reliability" (PDF).
files.diskeeper.com. Archived (PDF) from the original on 5 December
2014. Retrieved 29 November 2014.
Intel High Performance Solid State Drive - Solid State Drive
Frequently Asked Questions". Archived from the original on 2010-03-06.
^ "Windows Defragmenter". TechNet. Microsoft. 2010-04-23. Archived
from the original on 2017-08-26.
^ a b c d e Hanselman, Scott (3 December 2014). "The real and complete
story - Does Windows defragment your SSD?". Scott Hanselman's blog.
Microsoft. Archived from the original on 22 December 2014.
NTFS reserves space for its Master
File Table (MFT)".
Microsoft. 2008-10-16. Retrieved 2012-05-06.
^ "How does a solid state drive work?". Hardware. KnownHost. 27 May
2013. Archived from the original on 18 June 2013. Retrieved 17 June
^ "Do SSDs heat up?". Tom's Hardware. Retrieved 2012-05-06.
^ Meza, Justin; Wu, Qiang; Kumar, Sanjeev; Mutlu, Onur (2015). "A
Large-Scale Study of Flash Memory Failures in the Field" (PDF).
Archived (PDF) from the original on 2017-08-08.
Intel Solid-State Drive DC P3500 Series" (PDF). Intel. 2015-05-13.
Archived (PDF) from the original on 2015-07-01. Retrieved
^ "Poorly ventilated system cases can shorten the life of the hard
drive". Seagate. Archived from the original on 9 December 2013.
^ "Professional Data Recovery - The Data Rescue Center". The Data
Rescue Center. Archived from the original on 2015-11-27.
^ Lonely Planet. "Hard drives at high altitude". Archived from the
original on 2016-01-17.
^ "Dot Hill - Solid State Disks (SSDs)". Archived from the original on
^ a b Kaushik Patowary. "Interesting hard drive facts you probably
didn't know - Instant Fundas". Archived from the original on
USB hard drive and risk of internal condensation?".
Archived from the original on 2015-09-12.
^ a b "SSD vs HDD". SAMSUNG Semiconductor. Archived from the original
Memoright SSDs: The End of Hard drives?". Tom's Hardware. Retrieved
^ "Simple Installation Guide for Hitachi Deskstar 3.5-inch Hard Disk
Drives" (PDF). HGST. May 21, 2004. p. 2. Archived (PDF) from the
original on December 21, 2014. Retrieved December 4, 2014. Hitachi
Deskstar drive can be mounted with any side or end vertical or
horizontal. Do not mount the drive in a tilted position.
^ Peter Gutmann (2016-03-02). "Secure Deletion of Data from Magnetic
and Solid-State Memory". cs.auckland.ac.nz. Archived from the original
on 2016-06-06. Retrieved 2016-06-21.
^ "Hard Drive Destruction: Can I erase sensitive data on an old hard
drive with Neodymium Magnets?". kjmagnetics.com. Archived from the
original on 2016-06-30. Retrieved 2016-06-21.
^ "Myth #42: You can quickly degauss or erase a hard disk drive by
sweeping a magnet over it". techarp.com. 2015-12-17. Archived from the
original on 2016-07-03. Retrieved 2016-06-21.
^ Lucas Mearian (2008-08-27). "Solid-state disk lackluster for
laptops, PCs". Archived from the original on 2008-12-02. Retrieved
2008-09-12. Corporate-grade SSD uses single-level cell (SLC) NAND
memory and multiple channels to increase data throughput and
wear-leveling software to ensure data is distributed evenly in the
drive rather than wearing out one group of cells over another. And,
while some consumer-grade SSD is just now beginning to incorporate the
latter features (p. 1). It matters whether the SSD drive uses SLC or
MLC memory. SLC generally endures up to 100,000 write cycles or writes
per cell, while MLC can endure anywhere from 1,000 to 10,000 writes
before it begins to fail, [according to Fujitsu's vice president of
business development Joel Hagberg] (p. 4).
^ Kerekes, Zsolt. "SSD Myths and Legends - "write endurance"".
StorageSearch.com. ACSL. Archived from the original on
^ "No SWAP Partition, Journaling Filesystems, …on an SSD?".
Robert.penz.name. 2008-12-07. Archived from the original on
2009-11-02. Retrieved 2009-10-21.
^ "SSDs, Journaling, and noatime/relatime". 2009-03-01. Archived from
the original on 2011-08-08. Retrieved 2011-09-27.
^ Tests by Tom's Hardware on the 60 GB
Intel 520 SSD calculated a
worst-case lifetime of just over five years for incompressible data,
and a lifetime of 75 years for compressible data. Ku, Andrew (6
February 2012). "
Intel SSD 520 Review: SandForce's Technology: Very
Low Write Amplification". Tom's Hardware. Retrieved 10 February
^ Analysis of SSD Reliability during power-outages Archived 2014-01-01
at the Wayback Machine., December 2013
^ A study performed by
Carnegie Mellon University
Carnegie Mellon University on manufacturers'
published MTBF "Archived copy". Archived from the original on
2013-01-18. Retrieved 2013-02-23.
^ Ku, Andrew (29 July 2011). "Tom's Hardware, Data center feedback".
Tom's Hardware. Retrieved 10 February 2012.
^ "SSDs are hot, but not without security risks". IDG Communications.
2010-08-01. Archived from the original on 2010-12-27.
^ "Digital Storage Projections For 2018, Part 1".
December 20, 2017.
Flash memory should continue price decreases again
starting in 2018, but HDDs should be able to continue to maintain
something like a 10X difference in raw capacity prices out into the
next decade ...
^ a b "HDD vs SSD: What Does the Future for Storage Hold? — Part 2".
Backblaze, Inc. March 13, 2018.
^ Seagate’s new 60TB SSD is world’s largest Archived 2017-04-08 at
the Wayback Machine.
^ [Western Digital Announces Ultrastar He12 12 TB and 14 TB HDDs
"Archived copy". Archived from the original on 2017-01-19. Retrieved
^ "Archived copy" (PDF). Archived (PDF) from the original on
2014-01-23. Retrieved 2014-05-30.
AnandTech The SSD Improv:
Indilinx get TRIM, Kingston
Intel Down to $115". Anandtech. Archived from the original on
^ "Long-term performance analysis of
Intel Mainstream SSDs". PC
Perspective. 2009-02-13. Archived from the original on
^ Schmid, Patrick (2007-11-07). "HyperDrive 4 Redefines Solid State
Storage: HyperDrive 4 - The Fastest Hard Disk In The World?". Tom's
^ Prigge, Matt (2010-06-07). "An SSD crash course: What you need to
know". InfoWorld. Archived from the original on 2010-06-10. Retrieved
Toshiba 1.8 drive announcement, January 2011".
^ a b c "The differences between an SSD and a memory card".
sandisk.com. Retrieved 2011-06-16.
^ a b SSD reliability in the real world: Google's experience, ZDNet
2016. Also see full paper the article is based upon: Flash Reliability
in Production: The Expected and the Unexpected - Schroeder, Lagisetty
& Merchant, 2016.
^ a b
^ Null, Linda; Lobur, Julia (14 February 2014). The Essentials of
Computer Organization and Architecture. Jones & Bartlett Learning.
pp. 499–500. ISBN 978-1-284-15077-3.
Z68 Chipset &
Smart Response Technology (SSD Caching)
Review". AnandTech. Archived from the original on 2012-05-05.
^ "SSD Caching (Without Z68): HighPoint's RocketHybrid 1220". Tom's
Hardware. 2011-05-10. Retrieved 2012-05-06.
^ Mark E. Russinovich; David A. Solomon; Alex Ionescu (2009). Windows
internals (5th ed.).
Microsoft Press. pp. 772–774.
^ Petros Koutoupis (2013-11-25). "Advanced Hard Drive Caching
Techniques". linuxjournal.com. Archived from the original on
2013-12-02. Retrieved 2013-12-02.
Linux kernel 2.6.33". kernelnewbies.org. 2010-02-24. Archived from
the original on 2012-06-30. Retrieved 2013-11-05.
^ a b "swapon(8) –
Linux manual page". man7.org. 2013-09-17.
Archived from the original on 2013-07-14. Retrieved 2013-12-12.
^ a b "SSD Optimization". debian.org. 2013-11-22. Archived from the
original on 2013-07-05. Retrieved 2013-12-11.
^ a b "kernel/git/stable/linux-stable.git: mm/swapfile.c, line 2507
Linux kernel stable tree, version 3.12.5)". kernel.org. Retrieved
^ Tejun Heo. "LKML: Tejun Heo: [GIT PULL] libata changes for
v3.12-rc1". lkml.org. Archived from the original on 2016-01-17.
^ Michael Larabel (2013-11-19). "Ubuntu Aims To
TRIM SSDs By Default".
phoronix.com. Archived from the original on 2014-08-09. Retrieved
^ Karel Zak (2010-02-04). "Changes between v2.17 and v2.17.1-rc1,
commit 1a2416c6ed10fcbfb48283cae7e68ee7c7f1c43d". util-linux.
kernel.org. Archived from the original on 2013-05-25. Retrieved
^ "Enabling and Testing SSD
TRIM Support Under Linux". Techgage.
2011-05-06. Archived from the original on 2012-05-07. Retrieved
^ "openSUSE mailing list: SSD detection when creating first time
fstab ?". Lists.opensuse.org. 2011-06-02. Archived from the
original on 2011-06-17. Retrieved 2012-05-06.
^ "SSD discard (trim) support". openSUSE. Archived from the original
^ "Patrick Nagel: Impact of ext4′s discard option on my SSD".
Archived from the original on 2013-04-29.
^ "block/blk-lib.c, line 29". kernel/git/stable/linux-stable.git -
Linux kernel stable tree, version 3.12.7. kernel.org. Retrieved
Linux I/O Scheduler Comparison On The
Linux 3.4 Desktop". Phoronix.
2012-05-11. Archived from the original on 2013-10-04. Retrieved
^ "SSD benchmark of I/O schedulers". ubuntuforums.org. 2010. Archived
from the original on 2013-10-05. Retrieved 2013-10-03.
Linux kernel 3.13, Section 1.1 A scalable block layer for
high-performance SSD storage". kernelnewbies.org. 2014-01-19. Archived
from the original on 2014-01-25. Retrieved 2014-01-25.
Linux kernel 3.18, Section 1.8. Optional multiqueue
kernelnewbies.org. 2014-12-07. Archived from the original on
2014-12-18. Retrieved 2014-12-18.
^ Jonathan Corbet (2013-06-05). "The multiqueue block layer". LWN.net.
Archived from the original on 2014-01-25. Retrieved 2014-01-25.
^ Matias Bjørling; Jens Axboe; David Nellans; Philippe Bonnet (2013).
Linux Block IO: Introducing Multi-queue SSD Access on Multi-core
Systems" (PDF). kernel.dk. ACM. Archived (PDF) from the original on
2014-02-02. Retrieved 2014-01-25.
Linux kernel 4.0, Section 3. Block". kernelnewbies.org. 2015-05-01.
Archived from the original on 2015-05-04. Retrieved 2015-05-02.
^ "Mac OS X Lion has
TRIM support for SSDs, HiDPI resolutions for
improved pixel density?". Engadget. Archived from the original on
2011-06-29. Retrieved 2011-06-12.
^ "Yosemite 10.10.4 and El Capitan Third-Party SSD Support".
MacRumors. Archived from the original on 2015-09-26. Retrieved
^ "MacRumors Forum". MacRumors. Archived from the original on
2011-09-27. Retrieved 2011-06-12. [unreliable source?]
^ ATA Trim/Delete Notification Support in Windows 7 Archived
2013-07-28 at the Wayback Machine.
^ Yuri Gubanov; Oleg Afonin (2014). "Recovering Evidence from SSD
Drives: Understanding TRIM, Garbage Collection and Exclusions".
belkasoft.com. Archived from the original on January 22, 2015.
Retrieved January 22, 2015.
^ a b c Sinofsky, Steven (5 May 2009). "Support and Q&A for
Solid-State Drives". Engineering Windows 7. Microsoft. Archived from
the original on 30 June 2012.
^ Flynn, David (10 November 2008). "Windows 7 gets SSD-friendly". APC.
Future Publishing. Archived from the original on 1 February
^ Yam, Marcus (May 5, 2009). "Windows 7 and Optimization for Solid
State Drives". Tom's Hardware. Retrieved 9 August 2010.
^ "6 Things You Shouldn't Do With Solid-State Drives". Howtogeek.com.
Archived from the original on 13 March 2016. Retrieved 12 March
^ Smith, Tony. "If your SSD sucks, blame Vista, says SSD vendor".
Archived from the original on 2008-10-14. Retrieved 2008-10-11.
Microsoft in talks to speed up SSDs on Vista". Archived
from the original on 2009-02-05. Retrieved 2008-09-22.
^ Sexton, Koka (29 June 2010). "SSD Storage Demands Proper Partition
Alignment". www.wwpi.com. Archived from the original on 23 July 2010.
Retrieved 9 August 2010.
^ Butler, Harry (27 Aug 2009). "SSD performance tweaks for Vista".
bit-tech.net. Archived from the original on 27 July 2010. Retrieved 9
^ "Archived copy". Archived from the original on 2016-03-03. Retrieved
2016-02-23. Link to information
ZFS L2ARC and SSD drives by Brendan Gregg". brendan_entry_test. Sun
Microsystem blog. 2008-07-12. Archived from the original on
2009-08-30. Retrieved 2009-11-12.
^ "[base] Revision 240868". Svnweb.freebsd.org. Archived from the
original on 2012-10-25. Retrieved 2014-01-20.
^ Nemeth, Evi. UNIX and
Linux System Administration Handbook, 4/e.
ISBN 8131761770. Retrieved 25 November 2014.
^ a b "Support and Q&A for Solid-State Drives". Engineering
Windows 7. Microsoft.
^ "features". DragonFlyBSD. Archived from the original on 2012-05-09.
^ "[Phoronix] EnhanceIO,
Bcache & DM-Cache Benchmarked".
Phoronix.com. 2013-06-11. Archived from the original on 2013-12-20.
^ Peters, Lavon. "Solid State Storage For SQL Server". sqlmag.com.
Archived from the original on 28 March 2015. Retrieved 25 November
^ a b Aughton, Simon (2007-04-25). "
Dell Gets Flash With SSD Option
for Laptops". IT PRO. Archived from the original on 2008-09-17.
^ Chen, Shu-Ching Jean (2007-06-07). "$199 Laptop Is No Child's Play".
Forbes. Archived from the original on 2007-06-15. Retrieved
^ a b "Macbook Air Specifications".
Apple Inc. Archived from the
original on 2009-10-01. Retrieved 2009-10-21. [verification
^ "Road Warriors Get Ready –
Lenovo Delivers "No Compromises"
ThinkPad X300 Notebook PC" (Press release). Lenovo.
2008-02-26. Archived from the original on 2008-04-16.
^ Joshua Topolsky (2008-08-15). "
Lenovo slips out the new ThinkPad
X301: new CPUs, 128GB SSD, still thin as hell". engadget.com. Archived
from the original on 2013-12-12. Retrieved 2013-12-09.
^ "EMC With STEC for Enterprise Flash Drives". StorageNewsletter.com.
2008-01-14. Archived from the original on 2012-12-30. Retrieved
ZFS Enables Hybrid Storage Pools: Shatters Economic and
Performance Barriers" (PDF). Sun Microsystems. Archived (PDF) from the
original on 2009-02-19. Retrieved 2009-04-09.
^ Miller, Paul. "
Dell adds 256GB SSD option to XPS M1330 and M1730
laptops". engadget.com. Archived from the original on 24 September
2015. Retrieved 25 November 2014.
^ Crothers, Brooke. "
Dell first: 256GB solid-state drive on laptops".
www.cnet.com. Archived from the original on 2 September 2015.
Retrieved 25 November 2014.
Toshiba Ships First Laptop With a 512 GB SSD". Tom's Hardware.
Toshiba announces world's first 512GB SSD laptop". CNET News.
2009-04-14. Archived from the original on 2011-03-29.
^ "MacBook Air". Apple, Inc. 2010-10-20. Archived from the original on
2011-12-22. [verification needed]
^ "OCZ's RevoDrive X2: When A Fast
PCIe SSD Isn't Fast Enough". Tom's
^ "ioDrive Octal". Fusion-io. Archived from the original on
2012-11-01. Retrieved 2012-05-06.
^ Simms, Craig. "
MacBook Air vs. the ultrabook alternatives".
www.cnet.com. Archived from the original on 24 September 2015.
Retrieved 25 November 2014.
PCIe SSD Packs 16
SandForce SF-2200 Series Subunits".
techPowerUp. Archived from the original on 2012-05-18. Retrieved
^ Carl, Jack. "
OCZ Launches New Z-Drive R4 and R5
PCIe SSD – CES
2012". Lenzfire. Archived from the original on 2012-05-10. Retrieved
^ "Samsung Introduces Industry's First 1
global.samsungtomorrow.com, Samsung. 2013-12-09. Archived from the
original on 2014-12-19.
^ "Samsung announces 16TB SSD". ZDnet. ZDnet. Archived from the
original on 13 August 2015. Retrieved 13 August 2015.
^ Master, Neal; Andrews, Mathew; Hick, Jason; Canon, Shane; Wright,
Nicholas (2010). "Performance analysis of commodity and enterprise
class flash devices". IEEE Petascale Data Storage Workshop.
Intel X25-E 64GB G1, 4KB Random IOPS, iometer benchmark". March 27,
2010. Archived from the original on May 3, 2010. Retrieved
^ "SSDs vs. hard drives". Network World. Archived from the original on
^ SSD Sales up 14% in 2009 Archived 2013-06-15 at the Wayback
Machine., January 20th, 2010, Brian Beeler, storagereview.com
^ a b Solid State Drives to Score Big This Year with Huge Shipment
Growth Archived 2013-04-16 at the Wayback Machine., April 2, 2012,
Fang Zhang, iSupply
^ SSDs sales rise, prices drop below $1 per GB in 2012 Archived
2013-12-16 at the Wayback Machine., January 10, 2012, Pedro Hernandez,
^ 39 Million SSDs Shipped WW in 2012, Up 129% From 2011 - IHS iSuppli
Archived 2013-05-28 at the Wayback Machine., January 24th, 2013,
^ SSDs weather the PC storm Archived 2013-12-16 at the Wayback
Machine., May 8, 2013, Nermin Hajdarbegovic, TG Daily, accesat la 9
^ Samsung leads in 2008 SSD market with over 30% share, says Gartner
Archived 2013-06-03 at the Wayback Machine., 10 June 2009, Josephine
Lien, Taipei; Jessie Shen, DIGITIMES
"Solid-state revolution: in-depth on how SSDs really work". Lee
Hutchinson. Ars Technica. June 4, 2012.
Mai Zheng, Joseph Tucek, Feng Qin, Mark Lillibridge, "Understanding
the Robustness of SSDs under Power Fault", FAST'13
Cheng Li, Philip Shilane, Fred Douglis, Hyong Shim, Stephen Smaldone,
Grant Wallace, "Nitro: A Capacity-Optimized SSD Cache for Primary
Storage", USENIX ATC'14
Cheng Li, Philip Shilane, Fred Douglis, Grant Wallace, "Pannier: A
Container-based Flash Cache for Compound Objects[permanent dead
link]", ACM/IFIP/USENIX Middleware'15
Wikimedia Commons has media related to Solid-state drives.
Background and general
StorageReview.com SSD Guide
A guide to understanding Solid State Drives
SSDs versus laptop HDDs and upgrade experiences
Understanding SSDs and New Drives from OCZ
Charting the 30 Year Rise of the Solid State Disk Market
Investigation: Is Your SSD More Reliable Than A Hard Drive? - long
term SSD reliability review
SSD return rates review by manufacturer (2012), hardware.fr - French
(English) a 2012 update of a 2010 report based on data from a leading
French tech retailer
Enterprise SSD Form Factor Version 1.0a, SSD Form Factor Work Group,
December 12, 2012
Ted Tso - Aligning filesystems to an SSD's erase block size
JEDEC Continues SSD Standardization Efforts
Linux & NVM:
File and Storage System Challenges (PDF)
Linux and SSD Optimization
Understanding the Robustness of SSDs under Power Fault (USENIX 2013,
by Mai Zheng, Joseph Tucek, Feng Qin and Mark Lillibridge)
SSD vs. m.2, FrugalGaming, by James Heinfield
Flash file system
Flash memory controller
IM Flash Technologies
SanDisk and Toshiba
Indilinx (bankrupt, assets sold to Toshiba)
SandForce (now part of Seagate)
List of solid-state drive manufacturers
Advanced Host Controller Interface (AHCI)
Fibre Channel (FC)
NVM Express (NVMe)
PCI Express (PCIe)
Serial ATA (SATA)
Serial attached SCSI
Serial attached SCSI (SAS)
Universal Serial Bus
Universal Serial Bus (USB)
HDD form factors
PCI Express expansion card
JEDEC / JC-42, JC-64.8
NVMHCI Work Group
Basic computer components
Refreshable braille display
Refreshable braille display
USB flash drive
Central processing unit
Central processing unit (CPU)
HDD / SSD / SSHD
Network interface controller
Random-access memory (RAM)
FireWire (IEEE 1394)
HDMI / DVI / VG