|
UBIFS
UBIFS (UBI File System, more fully Unsorted Block Image File System) is a flash file system for unmanaged flash memory devices. UBIFS works on top of an UBI (unsorted block image) layer, which is itself on top of a memory technology device (MTD) layer. The file system is developed by Nokia engineers with help of the University of Szeged, Hungary. Development began in earnest in 2007, with the first stable release made to Linux kernel 2.6.27 in October 2008. Two major differences between UBIFS and JFFS2 are that UBIFS supports write caching, and UBIFS errs on the pessimistic side of free space calculation. UBIFS tends to perform better than JFFS2 for large NAND flash memory devices. This is a consequence of the UBIFS design goals: faster mounting, quicker access to large files, and improved write speeds. UBIFS also preserves or improves upon JFFS2's on-the-fly compression, recoverability and power fail tolerance. UBIFS's on-the-fly data compression allows zlib ( deflate algori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash File System
A flash file system is a file system designed for storing files on flash memory–based storage devices. While flash file systems are closely related to file systems in general, they are optimized for the nature and characteristics of flash memory (such as to avoid write amplification), and for use in particular operating systems. Overview While a block device layer can emulate a disk drive so that a general-purpose file system can be used on a flash-based storage device, this is suboptimal for several reasons: * Erasing blocks: flash memory blocks have to be explicitly erased before they can be written to. The time taken to erase blocks can be significant, thus it is beneficial to erase unused blocks while the device is idle. * Random access: general-purpose file systems are optimized to avoid disk seeks whenever possible, due to the high cost of seeking. Flash memory devices impose no seek latency. * Wear leveling: flash memory devices tend to wear out when a single blo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of File Systems
The following lists identify, characterize, and link to more thorough information on Computer file systems. Many older operating systems support only their one "native" file system, which does not bear any name apart from the name of the operating system itself. Disk file systems Disk file systems are usually block-oriented. Files in a block-oriented file system are sequences of blocks, often featuring fully random-access read, write, and modify operations. * ADFS – Acorn's Advanced Disc filing system, successor to DFS. * AdvFS – Advanced File System, designed by Digital Equipment Corporation for their Digital UNIX (now Tru64 UNIX) operating system. * APFS – Apple File System is a next-generation file system for Apple products. * AthFS – AtheOS File System, a 64-bit journaled filesystem now used by Syllable. Also called AFS. * BFS – the Boot File System used on System V release 4.0 and UnixWare. * BFS – the Be File System used on BeOS, occasionally misnamed as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JFFS2
Journalling Flash File System version 2 or JFFS2 is a log-structured file system for use with flash memory devices. It is the successor to JFFS. JFFS2 has been included into the Linux kernel since September 23, 2001, when it was merged into the Linux kernel mainline as part of the kernel version 2.4.10 release. JFFS2 is also available for a few bootloaders, like Das U-Boot, Open Firmware, the eCos RTOS, the RTEMS RTOS, and the RedBoot. Most prominent usage of the JFFS2 comes from OpenWrt. At least three file systems have been developed as JFFS2 replacements: LogFS, UBIFS, and YAFFS. Features JFFS2 introduced: * Support for NAND flash devices. This involved a considerable amount of work as NAND devices have a sequential I/O interface and cannot be memory-mapped for reading. * Hard links. This was not possible in JFFS because of limitations in the on-disk format. * Compression. Four algorithms are available: zlib, rubin, rtime, and lzo. * Better performance. JFFS treated the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nokia
Nokia Corporation (natively Nokia Oyj, referred to as Nokia) is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, established in 1865. Nokia's main headquarters are in Espoo, Finland, in the greater Helsinki Greater Helsinki, metropolitan area, but the company's actual roots are in the Tampere region of Pirkanmaa.HS: Nokian juuret ovat Tammerkosken rannalla (in Finnish) In 2020, Nokia employed approximately 92,000 people across over 100 countries, did business in more than 130 countries, and reported annual revenues of around €23 billion. Nokia is a public limited company listed on the Helsinki Stock Exchange and New York Stock Exchange. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NAND Flash
Flash memory is an Integrated circuit, electronic Non-volatile memory, non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR gate, NOR and NAND gate, NAND logic gates. Both use the same cell design, consisting of floating gate MOSFETs. They differ at the circuit level depending on whether the state of the bit line or word lines is pulled high or low: in NAND flash, the relationship between the bit line and the word lines resembles a NAND gate; in NOR flash, it resembles a NOR gate. Flash memory, a type of floating-gate memory, was invented at Toshiba in 1980 and is based on EEPROM technology. Toshiba began marketing flash memory in 1987. EPROMs had to be erased completely before they could be rewritten. NAND flash memory, however, may be erased, written, and read in blocks (or pages), which generally are much smaller than the entire device. NOR flash memo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embedded Linux
Operating systems based on the Linux kernel are used in embedded systems such as consumer electronics (eg. set-top boxes, smart TVs and personal video recorders (PVRs)), in-vehicle infotainment (IVI), networking equipment (such as routers, switches, wireless access points (WAPs) or wireless routers), machine control, industrial automation, navigation equipment, spacecraft flight software, and medical instruments in general. Because of their versatility, operating systems based on the Linux kernel can be also found in mobile devices that are actually touchscreen-based embedded devices, such as smartphones and tablets, together with personal digital assistants (PDAs) and portable media players that also include a touchscreen. This is a challenge for most learners because their computer experience is mainly based on GUI (Graphical user interface) based interaction with the machine and high-level programming on the one hand and low-level programming of small microcontrollers (MCU ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OLPC XO-1
The OLPC XO (formerly known as $100 Laptop, Children's Machine, 2B1) is a low cost laptop computer intended to be distributed to children in developing countries around the world, to provide them with access to knowledge, and opportunities to "explore, experiment and express themselves" (constructionist learning). The XO was developed by Nicholas Negroponte, a co-founder of MIT's Media Lab, and designed by Yves Behar's Fuseproject company. The laptop is manufactured by Quanta Computer and developed by One Laptop per Child (OLPC), a non-profit 501(c)(3) organization. The subnotebooks were designed for sale to government-education systems which then would give each primary school child their own laptop. Pricing was set to start at $188 in 2006, with a stated goal to reach the $100 mark in 2008 and the 50-dollar mark by 2010. When offered for sale in the Give One Get One campaigns of Q4 2006 and Q4 2007, the laptop was sold at $199. The rugged, low-power computers use flash mem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comparison Of File Systems
The following tables compare general and technical information for a number of file systems. General information Limits Metadata Features File capabilities Block capabilities Note that in addition to the below table, block capabilities can be implemented below the file system layer in Linux ( LVM, integritysetup, cryptsetup) or Windows (Volume Shadow Copy Service, SECURITY), etc. Resize capabilities "online" and "offline" are synonymous with "mounted" and "not mounted". Allocation and layout policies OS support See also * List of file systems * Comparison of file archivers * List of archive formats * Comparison of archive formats Notes References External links A speed comparison of filesystems on Linux 2.4.5(archived) Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch{{Webarchive, url=https://web.archive.org/web/20180304191727/https://debian-administration.org/article/388/Filesystems_ext3_reiser_xfs_jfs_comparison ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logical Volume Manager
In computer storage, logical volume management or LVM provides a method of allocating space on mass-storage devices that is more flexible than conventional partitioning schemes to store volumes. In particular, a volume manager can concatenate, stripe together or otherwise combine partitions (or block devices in general) into larger virtual partitions that administrators can re-size or move, potentially without interrupting system use. Volume management represents just one of many forms of storage virtualization; its implementation takes place in a layer in the device-driver stack of an operating system (OS) (as opposed to within storage devices or in a network). Design Most volume-manager implementations share the same basic design. They start with physical volumes (PVs), which can be either hard disks, hard disk partitions, or Logical Unit Numbers (LUNs) of an external storage device. Volume management treats each PV as being composed of a sequence of chunks called p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash Translation Layer
A flash memory controller (or flash controller) manages data stored on flash memory (usually NAND flash) and communicates with a computer or electronic device. Flash memory controllers can be designed for operating in low duty-cycle environments like memory cards, or other similar media for use in PDAs, mobile phones, etc. USB flash drives use flash memory controllers designed to communicate with personal computers through the USB port at a low duty-cycle. Flash controllers can also be designed for higher duty-cycle environments like solid-state drives (SSD) used as data storage for laptop computer systems up to mission-critical enterprise storage arrays. Initial setup After a flash storage device is initially manufactured, the flash controller is first used to format the flash memory. This ensures the device is operating properly, it maps out bad flash memory cells, and it allocates spare cells to be substituted for future failed cells. Some part of the spare cells is also u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squashfs
Squashfs is a compressed read-only file system for Linux. Squashfs compresses files, inodes and directories, and supports block sizes from 4 KiB up to 1 MiB for greater compression. Several compression algorithms are supported. Squashfs is also the name of free software, licensed under the GPL, for accessing Squashfs filesystems. Squashfs is intended for general read-only file-system use and in constrained block-device memory systems (e.g. embedded systems) where low overhead is needed. Uses Squashfs is used by the Live CD versions of Arch Linux, Debian, Fedora, Gentoo Linux, Linux Mint, openSUSE, Salix, Ubuntu, NixOS, Clonezilla, Kali Linux and on embedded distributions such as the OpenWrt and DD-WRT router firmware. It is also used in Chromecast and for the system partitions of some Android releases (Android Nougat). It is often combined with a union mount filesystem, such as UnionFS, OverlayFS, or aufs, to provide a read-write environment for live Linux distributions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
