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Union Mount
In computer operating systems, union mounting is a way of combining multiple directories into one that appears to contain their combined contents. Union mounting is supported in Linux, BSD and several of its successors, and Plan 9, with similar but subtly different behavior. As an example application of union mounting, consider the need to update the information contained on a CD-ROM or DVD. While a CD-ROM is not writable, one can overlay the CD's mount point with a writable directory in a union mount. Then, updating files in the union directory will cause them to end up in the writable directory, giving the illusion that the CD-ROM's contents have been updated. Implementations Plan 9 In the Plan 9 operating system from Bell Labs (mid-1980s onward), union mounting is a central concept, replacing several older Unix conventions with union directories; for example, several directories containing executables, unioned together at a single directory, replace the variable for c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as Computer program, programs. These programs enable computers to perform a wide range of tasks. A computer system is a nominally complete computer that includes the Computer hardware, hardware, operating system (main software), and peripheral equipment needed and used for full operation. This term may also refer to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of Programmable logic controller, industrial and Consumer electronics, consumer products use computers as control systems. Simple special-purpose devices like microwave ovens and remote controls are included, as are factory devices like industrial robots and computer-aided design, as well as general-purpose devi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory-mapped File
A memory-mapped file is a segment of virtual memory that has been assigned a direct byte-for-byte correlation with some portion of a file or file-like resource. This resource is typically a file that is physically present on disk, but can also be a device, shared memory object, or other resource that the operating system can reference through a file descriptor. Once present, this correlation between the file and the memory space permits applications to treat the mapped portion as if it were primary memory. History TOPS-20 PMAP An early () implementation of this was the PMAP system call on the DEC-20's TOPS-20 operating system, a feature used by Software House's System-1022 database system. SunOS 4 mmap SunOS 4 introduced Unix's mmap, which permitted programs "to map files into memory." Windows Growable Memory-Mapped Files (GMMF) Two decades after the release of TOPS-20's PMAP, Windows NT was given Growable Memory-Mapped Files (GMMF). Since " function requires a size to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GlusterFS
Gluster Inc. (formerly known as Z RESEARCH) was a software company that provided an open source platform for scale-out public and private cloud storage. The company was privately funded and headquartered in Sunnyvale, California, with an engineering center in Bangalore, India. Gluster was funded by Nexus Venture Partners and Index Ventures. Gluster was acquired by Red Hat on October 7, 2011. History The name ''Gluster'' comes from the combination of the terms ''GNU'' and ''cluster''. Despite the similarity in names, Gluster is not related to the Lustre file system and does not incorporate any Lustre code. Gluster based its product on ''GlusterFS'', an open-source software-based network-attached filesystem that deploys on commodity hardware. The initial version of GlusterFS was written by Anand Babu Periasamy, Gluster's founder and CTO. In May 2010 Ben Golub became the president and chief executive officer. Red Hat became the primary author and maintainer of the GlusterFS open ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phoronix
Phoronix Test Suite (PTS) is a free and open-source benchmark software for Linux and other operating systems which is developed by Michael Larabel and Matthew Tippett. The Phoronix Test Suite has been endorsed by sites such as Linux.com, LinuxPlanet, and Softpedia. Features * Supports over 220 test profiles and over 60 test suites; * Uses an XML-based testing architecture. Tests include MEncoder, FFmpeg and lm sensors along with OpenGL games such as '' Doom 3'', ''Nexuiz'', and '' Enemy Territory: Quake Wars'', and many more. * Contains a feature called PTS Global where users are able to upload their test results and system information for sharing. Then through executing a single command, other users can compare their test results to a selected system in an easy-comparison mode; * Allows report benchmark results to the Phoronix Global online database; * Allows to compare results side-by-side; * Is extensible and new tests can be added easily * Can do anonymous usage repo ... [...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 c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OverlayFS
In computing, OverlayFS is a union mount filesystem implementation for Linux. It combines multiple different underlying mount points into one, resulting in single directory structure that contains underlying files and sub-directories from all sources. Common applications overlay a read/write partition over a read-only partition, such as with LiveCDs and IoT devices with limited flash memory write cycles. History The need and specification of a kernel mode Linux union mount filesystem was identified in late 2009. The initial RFC patchset of OverlayFS was submitted by Miklos Szeredi in 2010. By 2011, OpenWrt had already adopted it for their use. It was merged into the Linux kernel mainline in 2014, in kernel version 3.18. It was improved in version 4.0, bringing improvements necessary for e.g. the storage driver in Docker. While most Live CD linux distributions used Aufs as of November 2016, Slackware used overlayfs for its live CD. Implementation The main mechanics of Overlay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aufs
aufs (short for advanced multi-layered unification filesystem) implements a union mount for Linux file systems. The name originally stood for AnotherUnionFS until version 2. Developed by Junjiro Okajima in 2006, aufs is a complete rewrite of the earlier UnionFS. It aimed to improve reliability and performance, but also introduced some new concepts, like writable branch balancing, and other improvements – some of which are now implemented in the UnionFS 2.x branch. aufs was rejected for merging into mainline Linux. Its code was criticized for being "dense, unreadable, nduncommented". Instead, OverlayFS was merged in the Linux kernel. After several attempts to merge aufs into mainline kernel, the author has given up. Use Aufs is included in Debian "Jessie" (v8) and Ubuntu 16.04 out of the box. Debian "Stretch" (v9) does not include aufs anymore, but provides a package aufs-dkms, which auto-compiles the aufs kernel module using Dell's dkms. Docker originally used aufs for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stony Brook University
Stony Brook University (SBU), officially the State University of New York at Stony Brook, is a public research university in Stony Brook, New York. Along with the University at Buffalo, it is one of the State University of New York system's two flagship institutions. Its campus consists of 213 buildings on over of land in Suffolk County and it is the largest public university (by area) in the state of New York. Opened in 1957 in Oyster Bay as the State University College on Long Island, the institution moved to Stony Brook in 1962. In 2001, Stony Brook was elected to the Association of American Universities, a selective group of major research universities in North America. It is also a member of the larger Universities Research Association. It is classified among "R1: Doctoral Universities – Very high research activity". Stony Brook University, in partnership with Battelle, manages Brookhaven National Laboratory, a national laboratory of the United States Depa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FiST
A fist is the shape of a hand when the fingers are bent inward against the palm and held there tightly. To make or clench a fist is to fold the fingers tightly into the center of the palm and then to clamp the thumb over the middle phalanges; in contrast to this "closed" fist, one keeps the fist "open" by holding the thumb against the side of the index finger. One uses the closed fist to punch the lower phalanges against a surface, or to pound with the little-finger side of the hand's heel; one uses the open fist to knock with the middle knuckle of the middle finger. Physiology and neurology Making a fist is virtually unknown among other primates. This is because while "most primate hands are long of palm and finger ndshort of thumb", the proportions are the opposite for humans. At least one study has claimed that the clenching of one's fist can be used to recall information. Some studies have shown that making fists can help humans to cope with stress or anxiety because th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UnionFS
Unionfs is a filesystem service for Linux, FreeBSD and NetBSD which implements a union mount for other file systems. It allows files and directories of separate file systems, known as branches, to be transparently overlaid, forming a single coherent file system. Contents of directories which have the same path within the merged branches will be seen together in a single merged directory, within the new, virtual filesystem. When mounting branches, the priority of one branch over the other is specified. So when both branches contain a file with the same name, one gets priority over the other. The different branches may be either ''read-only'' or ''read/write'' file systems, so that writes to the virtual, merged copy are directed to a specific real file system. This allows a file system to appear as writable, but without actually allowing writes to change the file system, also known as copy-on-write. This may be desirable when the media is physically read-only, such as in the case o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix File Types
The seven standard Unix file types are ''regular'', ''directory'', ''symbolic link'', ''FIFO special'', ''block special'', ''character special'', and ''socket'' as defined by POSIX. Different OS-specific implementations allow more types than what POSIX requires (e.g. Solaris doors). A file's type can be identified by the ls -l command, which displays the type in the first character of the file-system permissions field. For regular files, Unix does not impose or provide any internal file structure; therefore, their structure and interpretation is entirely dependent on the software using them. However, the file command can be used to determine what type of data they contain. Representations Numeric In the stat structure, file type and permissions (the mode) are stored together in a bit field, which has a size of at least 12 bits (3 bits to specify the type among the seven possible types of files; 9 bits for permissions). The layout for permissions is defined by POSIX to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spring (operating System)
Spring is a discontinued project in building an experimental microkernel-based object-oriented operating system (OS) developed at Sun Microsystems in the early 1990s. Using technology substantially similar to concepts developed in the Mach kernel, Spring concentrated on providing a richer programming environment supporting multiple inheritance and other features. Spring was also more cleanly separated from the operating systems it would host, divorcing it from its Unix roots and even allowing several OSes to be run at the same time. Development faded out in the mid-1990s, but several ideas and some code from the project was later re-used in the Java programming language libraries and the Solaris operating system. History Spring started in a roundabout fashion in 1987, as part of Sun and AT&T's collaboration to create a merged UNIX. Both companies decided it was also a good opportunity to "reimplement UNIX in an object-oriented fashion". However, after only a few meetings, this ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
