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Ext3
ext3, or third extended filesystem, is a journaled file system that is commonly used by the Linux kernel. It used to be the default file system for many popular Linux distributions. Stephen Tweedie first revealed that he was working on extending ext2 in ''Journaling the Linux ext2fs Filesystem'' in a 1998 paper, and later in a February 1999 kernel mailing list posting. The filesystem was merged with the mainline Linux kernel in November 2001 from 2.4.15 onward. Its main advantage over ext2 is journaling, which improves reliability and eliminates the need to check the file system after an unclean shutdown. Its successor is ext4. Advantages The performance (speed) of ext3 is less attractive than competing Linux filesystems, such as ext4, JFS, ReiserFS, and XFS, but ext3 has a significant advantage in that it allows in-place upgrades from ext2 without having to back up and restore data. Benchmarks suggest that ext3 also uses less CPU power than ReiserFS and XFS. It is als ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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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] |
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File System
In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stopped and the next began, or where any piece of data was located when it was time to retrieve it. By separating the data into pieces and giving each piece a name, the data are easily isolated and identified. Taking its name from the way a paper-based data management system is named, each group of data is called a " file". The structure and logic rules used to manage the groups of data and their names is called a "file system." There are many kinds of file systems, each with unique structure and logic, properties of speed, flexibility, security, size and more. Some file systems have been designed to be used for specific applications. For example, the ISO 9660 file system is desi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Stephen Tweedie
Stephen C. Tweedie is a Scottish software developer who is known for his work on the Linux kernel, in particular his work on filesystems. After becoming involved with the development of the ext2 filesystem working on performance issues, he led the development of the ext3 filesystem which involved adding a journaling layer ( JBD) to the ext2 filesystem. For his work on the journaling layer, he has been described by fellow Linux developer Andrew Morton as "a true artisan". Born in Edinburgh, Scotland in 1969, Tweedie studied computer science at Churchill College, Cambridge and the University of Edinburgh, where he did his thesis on ''Contention and Achieved Performance in Multicomputer Wormhole Routing Networks''. After contributing to the Linux kernel in his spare time since the early nineties and working on VMS filesystem support for DEC for two years, Tweedie was employed by Linux distributor Red Hat where he continues to work on the Linux kernel. Tweedie has published a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Access Control List
In computer security, an access-control list (ACL) is a list of permissions associated with a system resource (object). An ACL specifies which users or system processes are granted access to objects, as well as what operations are allowed on given objects. Each entry in a typical ACL specifies a subject and an operation. For instance, if a file object has an ACL that contains , this would give Alice permission to read and write the file and give Bob permission only to read it. Implementations Many kinds of operating systems implement ACLs or have a historical implementation; the first implementation of ACLs was in the filesystem of Multics in 1965. Filesystem ACLs A filesystem ACL is a data structure (usually a table) containing entries that specify individual user or group rights to specific system objects such as programs, processes, or files. These entries are known as access-control entries (ACEs) in the Microsoft Windows NT, OpenVMS, and Unix-like operating systems s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Journaling File System
A journaling file system is a file system that keeps track of changes not yet committed to the file system's main part by recording the goal of such changes in a data structure known as a " journal", which is usually a circular log. In the event of a system crash or power failure, such file systems can be brought back online more quickly with a lower likelihood of becoming corrupted. Depending on the actual implementation, a journaling file system may only keep track of stored metadata, resulting in improved performance at the expense of increased possibility for data corruption. Alternatively, a journaling file system may track both stored data and related metadata, while some implementations allow selectable behavior in this regard. History In 1990 IBM introduced JFS in AIX 3.1 as one of the first UNIX commercial filesystems that implemented journaling. The next year the idea was popularized in a widely cited paper on log-structured file systems. This was subsequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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ReiserFS
ReiserFS is a general-purpose, journaling file system initially designed and implemented by a team at Namesys led by Hans Reiser and licensed under GPLv2. Introduced in version 2.4.1 of the Linux kernel, it was the first journaling file system to be included in the standard kernel. ReiserFS was the default file system in Novell's SUSE Linux Enterprise until Novell decided to move to ext3 on October 12, 2006, for future releases. Namesys considered ReiserFS version 3.6 which introduced a new on-disk format allowing bigger filesizes, now occasionally referred to as Reiser3, as stable and feature-complete and, with the exception of security updates and critical bug fixes, ceased development on it to concentrate on its successor, Reiser4. Namesys went out of business in 2008 after Reiser's conviction for murder. The product is now maintained as open source by volunteers. The reiserfsprogs 3.6.27 were released on 25 July 2017. ReiserFS is currently supported on Linux without quo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Ext4
ext4 (fourth extended filesystem) is a journaling file system for Linux, developed as the successor to ext3. ext4 was initially a series of backward-compatible extensions to ext3, many of them originally developed by Cluster File Systems for the Lustre file system between 2003 and 2006, meant to extend storage limits and add other performance improvements. However, other Linux kernel developers opposed accepting extensions to ext3 for stability reasons, and proposed to fork the source code of ext3, rename it as ext4, and perform all the development there, without affecting existing ext3 users. This proposal was accepted, and on 28 June 2006, Theodore Ts'o, the ext3 maintainer, announced the new plan of development for ext4. A preliminary development version of ext4 was included in version 2.6.19 of the Linux kernel. On 11 October 2008, the patches that mark ext4 as stable code were merged in the Linux 2.6.28 source code repositories, denoting the end of the development ph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Journaling File System
A journaling file system is a file system that keeps track of changes not yet committed to the file system's main part by recording the goal of such changes in a data structure known as a " journal", which is usually a circular log. In the event of a system crash or power failure, such file systems can be brought back online more quickly with a lower likelihood of becoming corrupted. Depending on the actual implementation, a journaling file system may only keep track of stored metadata, resulting in improved performance at the expense of increased possibility for data corruption. Alternatively, a journaling file system may track both stored data and related metadata, while some implementations allow selectable behavior in this regard. History In 1990 IBM introduced JFS in AIX 3.1 as one of the first UNIX commercial filesystems that implemented journaling. The next year the idea was popularized in a widely cited paper on log-structured file systems. This was subsequent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Tebibyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as The Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The first bit is number 0, making the eighth bit number 7. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Back Up
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is " back up", whereas the noun and adjective form is "backup". Backups can be used to recover data after its loss from data deletion or corruption, or to recover data from an earlier time. Backups provide a simple form of disaster recovery; however not all backup systems are able to reconstitute a computer system or other complex configuration such as a computer cluster, active directory server, or database server. A backup system contains at least one copy of all data considered worth saving. The data storage requirements can be large. An information repository model may be used to provide structure to this storage. There are different types of data storage devices used for copying backups of data that is already in secondary storage onto archi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Gibibyte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit of memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit definition, network protocol documents such as The Internet Protocol () refer to an 8-bit byte as an octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the bit endianness. The first bit is number 0, making the eighth bit number 7. The size of the byte has historically been hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six-bit character code was an often-used implementation in early encoding systems, and computers using six-bit and nine-bit bytes were common in the 1960s. These systems often had memory words ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Kibibyte
The byte is a units of information, unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character (computing), character of text in a computer and for this reason it is the smallest address space, addressable unit of Computer memory, memory in many computer architectures. To disambiguate arbitrarily sized bytes from the common 8-bit computing, 8-bit definition, Computer network, network protocol documents such as Internet Protocol, The Internet Protocol () refer to an 8-bit byte as an Octet (computing), octet. Those bits in an octet are usually counted with numbering from 0 to 7 or 7 to 0 depending on the Endianness#Bit endianness, bit endianness. The first bit is number 0, making the eighth bit number 7. The size of the byte has historically been Computer hardware, hardware-dependent and no definitive standards existed that mandated the size. Sizes from 1 to 48 bits have been used. The six- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |