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Jffs
The Journaling Flash File System (or JFFS) is a log-structured file system for use on NOR flash memory devices on the Linux operating system. It has been superseded by JFFS2. Design Flash memory (specifically NOR flash) must be erased prior to writing. The erase process has several limitations: * Erasing is very slow (typically 1–100 ms per erase block, which is 103–105 times slower than reading data from the same region). * It is only possible to erase flash in large segments (usually 64 KiB or more), whereas it can be read or written in smaller blocks (often 512 bytes). * Flash memory can only be erased a limited number of times (typically 103–106) before it becomes worn out. These constraints combine to produce a profound asymmetry between patterns of read and write access to flash memory. In contrast, magnetic hard disk drives offer nearly symmetrical read and write access: read speed and write speed are nearly identical (as both are constrained by the rate at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Axis Communications
Axis Communications AB is a Swedish manufacturer of network cameras, access control, and network audio devices for the physical security and video surveillance industries. History Axis Communications was founded in 1984 by Martin Gren, Mikael Karlsson and Keith Bloodworth in Lund, Sweden.Diane Ritchey, Security Magazine.Security's 25 Most Influential" December 1, 2006. Retrieved November 9, 2011. The company developed and sold protocol converters and printer interfaces for the connection of PC printers in IBM mainframe and mini-computer environments.Security Solutions.Axis celebrates 25 years in the network business" November 1, 2009. Retrieved August 17, 2011. By the end of the 1980s, Axis Communications had opened its first U.S. sales office in Boston, Massachusetts and, in the early 1990s, started shifting its focus away from IBM mainframes towards networking and the TCP/IP protocol. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Allocation Table
File Allocation Table (FAT) is a file system developed for personal computers. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. It is often supported for compatibility reasons by current operating systems for personal computers and many mobile devices and embedded systems, allowing interchange of data between disparate systems. The increase in disk drives capacity required three major variants: FAT12, FAT16 and FAT32. The FAT standard has also been expanded in other ways while generally preserving backward compatibility with existing software. FAT is no longer the default file system for Microsoft Windows computers. FAT file systems are still commonly found on floppy disks, flash and other solid-state memory cards and modules (including USB flash drives), as well as many portable and embedded devices. FAT is the standard file system for digital cameras per the DCF specification. Overview Concepts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YAFFS
Yaffs (Yet Another Flash File System) is a file system designed and written by Charles Manning for the company Aleph One. Yaffs1 was the first version of this file system and was designed for the then-current NAND chips with 512 byte page size (+ 16 byte spare (OOB;Out-Of-Band) area). Work started in 2002, and it was first released later that year. The initial work was sponsored by Toby Churchill Ltd, and Brightstar Engineering. These older chips also generally allow 2 or 3 write cycles per page. YAFFS takes advantage of this: dirty pages are marked by writing to a specific spare area byte. Newer NAND flash chips have larger pages, first 2K pages (+ 64 bytes OOB), later 4K, with stricter write requirements. Each page within an erase block (128 kilobytes) must be written to in sequential order, and each page must be written only once. Designing a storage system that enforces a "write once rule" ("write once property") has several advantages. YAFFS2 was designed to accommodate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NILFS
NILFS or NILFS2 (''New Implementation of a Log-structured File System'') is a log-structured file system implementation for the Linux kernel. It was developed by Nippon Telegraph and Telephone Corporation (NTT) CyberSpace Laboratories and a community from all over the world. NILFS was released under the terms of the GNU General Public License (GPL). Design "NILFS is a log-structured file system, in that the storage medium is treated like a circular buffer and new blocks are always written to the end. ��og-structured file systems are often used for flash media since they will naturally perform wear-leveling; ��ILFS emphasizes snapshots. The log-structured approach is a specific form of copy-on-write behavior, so it naturally lends itself to the creation of file system snapshots. The NILFS developers talk about the creation of "continuous snapshots" which can be used to recover from user-initiated file system problems ��" Using a copy-on-write technique known as "nothing in life i ... [...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] |
Garbage Collection (computer Science)
In computer science, garbage collection (GC) is a form of automatic memory management. The ''garbage collector'' attempts to reclaim memory which was allocated by the program, but is no longer referenced; such memory is called '' garbage''. Garbage collection was invented by American computer scientist John McCarthy around 1959 to simplify manual memory management in Lisp. Garbage collection relieves the programmer from doing manual memory management, where the programmer specifies what objects to de-allocate and return to the memory system and when to do so. Other, similar techniques include stack allocation, region inference, and memory ownership, and combinations thereof. Garbage collection may take a significant proportion of a program's total processing time, and affect performance as a result. Resources other than memory, such as network sockets, database handles, windows, file descriptors, and device descriptors, are not typically handled by garbage collection, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wear Levelling
Wear leveling (also written as wear levelling) is a technique Wear leveling techniques for flash memory systems. for prolonging the service life of some kinds of erasable computer storage media, such as flash memory, which is used in solid-state drives (SSDs) and USB flash drives, and phase-change memory. There are several wear leveling mechanisms that provide varying levels of longevity enhancement in such memory systems. The term ''preemptive wear leveling'' (PWL) has been used by Western Digital to describe their preservation technique used on hard disk drives (HDDs) designed for storing audio and video data. However, HDDs generally are not wear-leveled devices in the context of this article. Rationale EEPROM and flash memory media have individually erasable segments, each of which can be put through a limited number of erase cycles before becoming unreliable. This is usually around 3,000/5,000 cycles but many flash devices have one block with a specially extended life of 100, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ext2
The ext2 or second extended file system is a file system for the Linux kernel. It was initially designed by French software developer Rémy Card as a replacement for the extended file system (ext). Having been designed according to the same principles as the Berkeley Fast File System from BSD, it was the first commercial-grade filesystem for Linux. The canonical implementation of ext2 is the "ext2fs" filesystem driver in the Linux kernel. Other implementations (of varying quality and completeness) exist in GNU Hurd, MINIX 3, some BSD kernels, in MiNT, Haiku and as third-party Microsoft Windows and macOS drivers. ext2 was the default filesystem in several Linux distributions, including Debian and Red Hat Linux, until supplanted by ext3, which is almost completely compatible with ext2 and is a journaling file system. ext2 is still the filesystem of choice for flash-based storage media (such as SD cards and USB flash drives) because its lack of a journal increases perfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which includes the kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name "GNU/Linux" to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian, Fedora Linux, and Ubuntu, the latter of which itself consists of many different distributions and modifications, including Lubuntu and Xubuntu. Commercial distributions include Red Hat Enterprise Linux and SUSE Linux Enterprise. Desktop Linux distributions include a windowing system such as X11 or Wayland, and a desktop environment such as GNOME or KDE Plasma. Distributions inten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advanced Format
Advanced Format (AF) is any disk sector format used to store data on magnetic disks in hard disk drives (HDDs) that exceeds 512, 520, or 528 bytes per sector, such as the 4096, 4112, 4160, and 4224-byte (4 KB) sectors of an Advanced Format Drive (AFD). Larger sectors enable the integration of stronger error correction algorithms to maintain data integrity at higher storage densities. History The use of long data sectors was suggested in 1998 in a technical paper issued by the National Storage Industry Consortium (NSIC) calling attention to the conflict between continuing increases in areal density and the traditional 512-byte-per-sector format used in hard disk drives. Without revolutionary breakthroughs in magnetic recording system technologies, areal densities, and with them the storage capacities, hard disk drives were projected to stagnate. The storage industry trade organization, International Disk Drive Equipment and Materials Association (IDEMA), responded by organ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash Memory
Flash memory is an electronic 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 and 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 memory allows a single machine word to be written to an er ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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