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Hard Disk Drive Performance Characteristics
Higher performance in hard disk drives comes from devices which have better performance characteristics. These performance characteristics can be grouped into two categories: access time and data transfer time (or rate). Access time The ''access time'' or ''response time'' of a rotating drive is a measure of the time it takes before the drive can actually transfer data. The factors that control this time on a rotating drive are mostly related to the mechanical nature of the rotating disks and moving heads. It is composed of a few independently measurable elements that are added together to get a single value when evaluating the performance of a storage device. The access time can vary significantly, so it is typically provided by manufacturers or measured in benchmarks as an average. The key components that are typically added together to obtain the access time are: * Seek time * Rotational latency * Command processing time * Settle time Seek time With rotating drives, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Storage
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer is what manipulates data by performing computations. In practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but less expensive and larger options further away. Generally, the fast volatile technologies (which lose data when off power) are referred to as "memory", while slower persistent technologies are referred to as "storage". Even the first computer designs, Charles Babbage's Analytical Engine and Percy Ludgate's Analytical Machine, clearly distinguished between processing and memory (Babbage stored numbers as rotations of gears, while Ludgate stored numbers as displacements of rods in shuttles). This distinction was extended in the Von Neumann a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk Drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box. Introduced by IBM in 1956, HDDs were the dominant secondary storage device for general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern era of servers and personal computers, though personal computing devices produced in large volume, like cell phones and tablets, rely on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Storage
Disk storage (also sometimes called drive storage) is a general category of storage mechanisms where data is recorded by various electronic, magnetic, optical, or mechanical changes to a surface layer of one or more rotating disks. A disk drive is a device implementing such a storage mechanism. Notable types are the hard disk drive (HDD) containing a non-removable disk, the floppy disk drive (FDD) and its removable floppy disk, and various optical disc drives (ODD) and associated optical disc media. (The spelling ''disk'' and ''disc'' are used interchangeably except where trademarks preclude one usage, e.g. the Compact Disc logo. The choice of a particular form is frequently historical, as in IBM's usage of the ''disk'' form beginning in 1956 with the " IBM 350 disk storage unit".) Background Audio information was originally recorded by analog methods (see Sound recording and reproduction). Similarly the first video disc used an analog recording method. In the music indu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk Drive
A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating platters coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces. Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data when powered off. Modern HDDs are typically in the form of a small rectangular box. Introduced by IBM in 1956, HDDs were the dominant secondary storage device for general-purpose computers beginning in the early 1960s. HDDs maintained this position into the modern era of servers and personal computers, though personal computing devices produced in large volume, like cell phones and tablets, rely on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disk Sector
In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user-accessible data, traditionally 512 bytes for hard disk drives (HDDs) and 2048 bytes for CD-ROMs and DVD-ROMs. Newer HDDs use 4096-byte (4 KiB) sectors, which are known as the Advanced Format (AF). The sector is the minimum storage unit of a hard drive. Most disk partitioning schemes are designed to have files occupy an integral number of sectors regardless of the file's actual size. Files that do not fill a whole sector will have the remainder of their last sector filled with zeroes. In practice, operating systems typically operate on blocks of data, which may span multiple sectors. Geometrically, the word sector means a portion of a disk between a center, two radii and a corresponding arc (see Figure 1, item B), which is shaped like a slice of a pie. Thus, the ''disk sector'' (Figure 1, item C) refers to the intersection of a ''t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotation
Rotation, or spin, is the circular movement of an object around a '' central axis''. A two-dimensional rotating object has only one possible central axis and can rotate in either a clockwise or counterclockwise direction. A three-dimensional object has an infinite number of possible central axes and rotational directions. If the rotation axis passes internally through the body's own center of mass, then the body is said to be ''autorotating'' or '' spinning'', and the surface intersection of the axis can be called a ''pole''. A rotation around a completely external axis, e.g. the planet Earth around the Sun, is called ''revolving'' or ''orbiting'', typically when it is produced by gravity, and the ends of the rotation axis can be called the ''orbital poles''. Mathematics Mathematically, a rotation is a rigid body movement which, unlike a translation, keeps a point fixed. This definition applies to rotations within both two and three dimensions (in a plane and in space, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seagate Technology
Seagate Technology Holdings plc is an American data storage company. It was incorporated in 1978 as Shugart Technology and commenced business in 1979. Since 2010, the company has been incorporated in Dublin, Ireland, with operational headquarters in Fremont, California, United States. Seagate developed the first 5.25-inch hard disk drive (HDD), the 5-megabyte ST-506, in 1980. They were a major supplier in the microcomputer market during the 1980s, especially after the introduction of the IBM XT in 1983. Much of their growth has come through their acquisition of competitors. In 1989, Seagate acquired Control Data Corporation's Imprimis division, the makers of CDC's HDD products. Seagate acquired Conner Peripherals in 1996, Maxtor in 2006, and Samsung's HDD business in 2011. Today, Seagate, along with its competitor Western Digital, dominates the HDD market. History Founding as Shugart Technology Seagate Technology (then called Shugart Technology) was incorporated on No ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Automatic Acoustic Management
Automatic acoustic management (AAM) is a method for reducing acoustic emanations in AT Attachment (ATA) mass storage devices for computer data storage, such as ATA hard disk drives and ATAPI optical disc drives. AAM is an optional feature set for ATA/ATAPI devices; when a device supports AAM, the acoustic management parameters are adjustable through a software or firmware user interface. Details The ATA/ATAPI sub-command for setting the level of AAM operation is an 8-bit value from 0 to 255. Most modern drives ship with the vendor-defined value of 0x00 in the acoustic management setting. This often translates to the max-performance value of 254 stated in the standard. Values between 128 and 254 (0x80 - 0xFE) enable the feature and select most-quiet to most-performance settings along that range. Though hard drive manufacturers may support the whole range of values, the settings are allowed to be banded, so many values could provide the same acoustic performance. Although there i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluid Bearing
Fluid bearings are bearings in which the load is supported by a thin layer of rapidly moving pressurized liquid or gas between the bearing surfaces. Since there is no contact between the moving parts, there is no sliding friction, allowing fluid bearings to have lower friction, wear and vibration than many other types of bearings. Thus, it is possible for some fluid bearings to have near-zero wear if operated correctly. They can be broadly classified into two types: fluid dynamic bearings (also known as hydrodynamic bearings) and hydrostatic bearings. Hydrostatic bearings are externally pressurized fluid bearings, where the fluid is usually oil, water or air, and is pressurized by a pump. Hydrodynamic bearings rely on the high speed of the journal (the part of the shaft resting on the fluid) to pressurize the fluid in a wedge between the faces. Fluid bearings are frequently used in high load, high speed or high precision applications where ordinary ball bearings would have shor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quiet PC
A quiet, silent or fanless PC is a personal computer that makes very little or no noise. Common uses for quiet PCs include video editing, sound mixing and home theater PCs, but noise reduction techniques can also be used to greatly reduce the noise from servers. There is currently no standard definition for a "quiet PC", and the term is generally not used in a business context, but by individuals and the businesses catering to them. A proposed general definition is that the sound emitted by such PCs should not exceed 30 dBA, but in addition to the average sound pressure level, the frequency spectrum and dynamics of the sound are important in determining if the sound of the computer is noticed. Sounds with a smooth frequency spectrum (lacking audible tonal peaks), and little temporal variation are less likely to be noticed. The character and amount of other noise in the environment also affects how much sound will be noticed or masked, so a computer may be quiet with relation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Video Recorder
A digital video recorder (DVR) is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to disk recording, portable media players and TV gateways with recording capability, and digital camcorders. Personal computers are often connected to video capture devices and used as DVRs; in such cases the application software used to record video is an integral part of the DVR. Many DVRs are classified as consumer electronic devices; such devices may alternatively be referred to as personal video recorders (PVRs), particularly in Canada. Similar small devices with built-in (~5 inch diagonal) displays and SSD support may be used for professional film or video production, as these recorders often do not have the limitations that built-in recorders in cameras have, offering wider codec support, the removal of recording time limitations and hig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-weighting
A-weighting is the most commonly used of a family of curves defined in the International standard IEC 61672:2003 and various national standards relating to the measurement of sound pressure level. A-weighting is applied to instrument-measured sound levels in an effort to account for the relative loudness perceived by the human ear, as the ear is less sensitive to low audio frequencies. It is employed by arithmetically adding a table of values, listed by octave or third-octave bands, to the measured sound pressure levels in dB. The resulting octave band measurements are usually added (logarithmic method) to provide a single A-weighted value describing the sound; the units are written as dB(A). Other weighting sets of values – B, C, D and now Z – are discussed below. The curves were originally defined for use at different average sound levels, but A-weighting, though originally intended only for the measurement of low-level sounds (around 40 phon), is now commonly used for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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