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JFS2
Journaled File System (JFS) is a 64-bit journaling file system created by IBM. There are versions for AIX, OS/2, eComStation, ArcaOS and Linux operating systems. The latter is available as free software under the terms of the GNU General Public License (GPL). HP-UX has another, different filesystem named JFS that is actually an OEM version of Veritas Software's VxFS. In the AIX operating system, two generations of JFS exist, which are called ''JFS'' (''JFS1'') and ''JFS2'' respectively. IBM's JFS was originally designed for 32-bit systems. JFS2 was designed for 64-bit systems. In other operating systems, such as OS/2 and Linux, only the second generation exists and is called simply ''JFS''. This should not be confused with JFS in AIX that actually refers to JFS1. History IBM introduced JFS with the initial release of AIX version 3.1 in February 1990. This file system, now called ''JFS1 on AIX'', was the premier file system for AIX over the following decade and was install ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AIX Operating System
AIX (pronounced ) is a series of proprietary Unix operating systems developed and sold by IBM since 1986. The name stands for "Advanced Interactive eXecutive". Current versions are designed to work with Power ISA based server and workstation computers such as IBM's Power line. Background Originally released for the IBM RT PC RISC workstation in 1986, AIX has supported a wide range of hardware platforms, including the IBM RS/6000 series and later Power and PowerPC-based systems, IBM System i, System/370 mainframes, PS/2 personal computers, and the Apple Network Server. Currently, it is supported on IBM Power Systems alongside IBM i and Linux. AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is certified to the UNIX 03 and UNIX V7 specifications of the Single UNIX Specification, beginning with AIX versions 5.3 and 7.2 TL5, respectively. Older versions were certified to the UNIX 95 and UNIX 98 specifications. AIX was the first operating system to imp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM AIX
AIX (pronounced ) is a series of Proprietary software, proprietary Unix operating systems developed and sold by IBM since 1986. The name stands for "Advanced Interactive eXecutive". Current versions are designed to work with Power ISA based Server (computing), server and workstation computers such as IBM's IBM Power Systems, Power line. Background Originally released for the IBM RT PC Reduced instruction set computer, RISC workstation in 1986, AIX has supported a wide range of hardware platforms, including the IBM IBM RS/6000, RS/6000 series and later IBM Power microprocessors, Power and PowerPC-based systems, IBM System i, System/370 mainframes, IBM PS/2, PS/2 personal computers, and the Apple Network Server. Currently, it is supported on IBM Power Systems alongside IBM i and Linux. AIX is based on UNIX System V with 4.3BSD-compatible extensions. It is certified to the UNIX 03 and UNIX V7 specifications of the Single UNIX Specification, beginning with AIX versions 5.3 an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extent (file Systems)
In computing, an extent is a contiguous area of storage reserved for a file in a file system, represented as a range of block numbers, or tracks on count key data devices. A file can consist of zero or more extents; one file fragment requires one extent. The direct benefit is in storing each range compactly as two numbers, instead of canonically storing every block number in the range. Also, extent allocation results in less file fragmentation. Extent-based file systems can also eliminate most of the metadata overhead of large files that would traditionally be taken up by the block-allocation tree. But because the savings are small compared to the amount of stored data (for all file sizes in general) but make up a large portion of the metadata (for large files), the overall benefits in storage efficiency and performance are slight. In order to resist fragmentation, several extent-based file systems do allocate-on-flush. Many modern fault-tolerant file systems also do cop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
HP-UX
HP-UX (from "Hewlett Packard Unix") is a proprietary software, proprietary implementation of the Unix operating system developed by Hewlett Packard Enterprise; current versions support HPE Integrity Servers, based on Intel's Itanium architecture. It is based on Unix System V (initially Unix System III, System III) and first released in 1984. Earlier versions of HP-UX supported the HP Integral PC and HP 9000 Series 200, 300, and 400 computer systems based on the Motorola 68000 series of processors, the HP 9000 Series 500 computers based on HP's proprietary HP FOCUS, FOCUS architecture, and later HP 9000 Series models based on HP's PA-RISC instruction set architecture. HP-UX was the first Unix to offer access-control lists for file access permissions as an alternative to the standard Unix permissions system. HP-UX was also among the first Unix systems to include a built-in logical volume management, logical volume manager. HP has had a long partnership with Veritas Software, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ext3
ext3, or third extended filesystem, is a journaling file system, journaled file system that is commonly used with the Linux kernel. It used to be the default file system for many popular Linux distributions but generally has been supplanted by its successor version ext4. The main advantage of ext3 over its predecessor, ext2, is journaling file system, journaling, which improves reliability and eliminates the need to check the file system after an unclean or improper Shutdown (computing), shutdown. History 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. Advantages The speed performance of ext3 is less attractive than competing Linux filesystems, such as ext4, JFS (file system), JFS, ReiserFS, and XFS, but ext3 has a significant advantage in tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Drive
A solid-state drive (SSD) is a type of solid-state storage device that uses integrated circuits to store data persistently. It is sometimes called semiconductor storage device, solid-state device, or solid-state disk. SSDs rely on non-volatile memory, typically NAND flash, to store data in memory cells. The performance and endurance of SSDs vary depending on the number of bits stored per cell, ranging from high-performing single-level cells (SLC) to more affordable but slower quad-level cells (QLC). In addition to flash-based SSDs, other technologies such as 3D XPoint offer faster speeds and higher endurance through different data storage mechanisms. Unlike traditional hard disk drives (HDDs), SSDs have no moving parts, allowing them to deliver faster data access speeds, reduced latency, increased resistance to physical shock, lower power consumption, and silent operation. Often interfaced to a system in the same way as HDDs, SSDs are used in a variety of devices, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trim (computing)
A trim command (known as TRIM in the ATA command set, and UNMAP in the SCSI command set) allows an operating system to inform a solid-state drive (SSD) which blocks of data are no longer considered to be "in use" and therefore can be erased internally. Trim was introduced soon after SSDs were introduced. Because low-level operation of SSDs differs significantly from hard drives, the conventional manner in which operating systems handle storage operations—such as deletions and formatting—resulted in unanticipated progressive performance degradation of write operations on SSDs. Trimming enables the SSD to more efficiently handle garbage collection, which would otherwise slow future write operations to the involved blocks.Shimpi, Anand Lal. (18 March 2009). p. 10. TRIM is an ATA command (Advanced Technology Attachment Command) that allows an OS to inform SSD about the blocks of data no longer in use. The SSD then deletes such blocks of data to make a way for newer blocks of da ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Software Bugs
A software bug is a design defect ( bug) in computer software. A computer program with many or serious bugs may be described as ''buggy''. The effects of a software bug range from minor (such as a misspelled word in the user interface) to severe (such as frequent crashing). In 2002, a study commissioned by the US Department of Commerce's National Institute of Standards and Technology concluded that "software bugs, or errors, are so prevalent and so detrimental that they cost the US economy an estimated $59 billion annually, or about 0.6 percent of the gross domestic product". Since the 1950s, some computer systems have been designed to detect or auto-correct various software errors during operations. History Terminology ''Mistake metamorphism'' (from Greek ''meta'' = "change", ''morph'' = "form") refers to the evolution of a defect in the final stage of software deployment. Transformation of a ''mistake'' committed by an analyst in the early stages of the softwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linux Kernel
The Linux kernel is a Free and open-source software, free and open source Unix-like kernel (operating system), kernel that is used in many computer systems worldwide. The kernel was created by Linus Torvalds in 1991 and was soon adopted as the kernel for the GNU operating system (OS) which was created to be a free software, free replacement for Unix. Since the late 1990s, it has been included in many Linux distributions, operating system distributions, many of which are called Linux. One such Linux kernel operating system is Android (operating system), Android which is used in many mobile and embedded devices. Most of the kernel code is written in C (programming language), C as supported by the GNU compiler collection (GCC) which has extensions beyond standard C. The code also contains assembly language, assembly code for architecture-specific logic such as optimizing memory use and task execution. The kernel has a Modular programming, modular design such that modules can be inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM Linux Technology Center
The IBM Linux Technology Center (LTC) is an organization focused on development for the Linux kernel and related open-source software projects. In 1999, IBM created the LTC to combine its software developers interested in Linux and other open-source software into a single organization. Much of the LTC's early effort was focused on making "all of its server platforms Linux friendly." The LTC collaborated with the Linux community to make Linux run optimally on processor architectures such as x86, mainframe, PowerPC, and Power ISA. In recent years, the focus of the LTC has expanded to include several other open source initiatives. With about 185 IBM employees working for the LTC in 1999, this number grew steadily to about 600 in 2006, 300 of whom worked full-time on Linux. In December 2000, IBM claimed to have invested approximately one billion US dollars in Linux by the year 2000, and to currently have about 1,500 developers working on the alternative operating system. It announced th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Open-source Model
Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentralized software development model that encourages open collaboration. A main principle of open source software development is peer production, with products such as source code, blueprints, and documentation freely available to the public. The open source movement in software began as a response to the limitations of proprietary code. The model is used for projects such as in open source appropriate technology, and open source drug discovery. Open source promotes universal access via an open-source or free license to a product's design or blueprint, and universal redistribution of that design or blueprint. Before the phrase ''open source'' became widely adopted, developers and producers used a variety of other terms, such as ''free software'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
