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Journaling Block Device
JBD, or journaling block device, is a generic block device Journaling file system, journaling layer in the Linux kernel written by Stephen Tweedie from Red Hat. JBD is filesystem-independent. ext3, ext4 and OCFS2 are known to use JBD. JBD exists in two versions, JBD and JBD2. JBD was created with ext3 in 1998. JBD2 was forked from JBD in 2006 with ext4, with the goal of supporting a 64-bit (as opposed to 32-bit-only in JBD) block number. As a result, the maximum volume size in ext4 is increased to 1 Exbibyte, EiB compared to 16 Tebibyte, TiB in ext3 (assuming 4 KiB blocks). JBD2 is backward-compatible. OCFS2 starting from Linux 2.6.28 uses JBD2. The old JBD was removed with the dedicated ext3 driver in Linux 4.3 (2015). JBD structures Atomic handle An atomic handle is basically a collection of all the low-level changes that occur during a single high-level atomic update to the file system. The atomic handle guarantees that the high-level update either happens or not, because the a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 subsequently i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU operating system, which was written to be a free (libre) replacement for Unix. Linux is provided under the GNU General Public License version 2 only, but it contains files under other compatible licenses. Since the late 1990s, it has been included as part of a large number of operating system distributions, many of which are commonly also called Linux. Linux is deployed on a wide variety of computing systems, such as embedded devices, mobile devices (including its use in the Android operating system), personal computers, servers, mainframes, and supercomputers. It can be tailored for specific architectures and for several usage scenarios using a family of simple commands (that is, without the need of manually editing its source code ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Hat
Red Hat, Inc. is an American software company that provides open source software products to enterprises. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina, with other offices worldwide. Red Hat has become associated to a large extent with its enterprise operating system Red Hat Enterprise Linux. With the acquisition of open-source enterprise middleware vendor JBoss, Red Hat also offers Red Hat Virtualization (RHV), an enterprise virtualization product. Red Hat provides storage, operating system platforms, middleware, applications, management products, and support, training, and consulting services. Red Hat creates, maintains, and contributes to many free software projects. It has acquired several proprietary software product codebases through corporate mergers and acquisitions and has released such software under open source licenses. , Red Hat is the second largest corporate contributor to the Linux kernel version 4.14 after Intel. On Octob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 also cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 phase ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OCFS2
The Oracle Cluster File System (OCFS, in its second version OCFS2) is a shared disk file system developed by Oracle Corporation and released under the GNU General Public License. The first version of OCFS was developed with the main focus to accommodate Oracle's database management system that used cluster computing. Because of that it was not a POSIX-compliant file system. With version 2 the POSIX features were included. OCFS2 (version 2) was integrated into the version 2.6.16 of Linux kernel. Initially, it was marked as "experimental" ( Alpha-test) code. This restriction was removed in Linux version 2.6.19. With kernel version 2.6.29 in late 2008, more features were included into ocfs2, such as access control lists and quotas. OCFS2 used a distributed lock manager which resembles the OpenVMS DLM but is much simpler. Oracle announced version 1.6 in November 2010 which included a copy on write feature called reflink. See also * GlusterFS * GFS2 * General Parallel File System (GP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exbibyte
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] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel Features
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 intended for se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux File System-related Software
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 intended for servers may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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