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Snapshot (computer Storage)
In Computer, computer systems, a snapshot is the State (computer science), state of a system at a particular point in time. The term was coined as an analogy to that in Snapshot (photography), photography. Rationale A full backup of a large data set may take a long time to complete. On Computer multitasking, multi-tasking or multi-user systems, there may be writes to that data while it is being backed up. This prevents the backup from being Atomicity (database systems), atomic and introduces a version skew that may result in data corruption. For example, if a user moves a file into a directory that has already been backed up, then that file would be completely missing on the Computer data storage, backup media, since the backup operation had already taken place before the addition of the file. Version skew may also cause corruption with files which change their size or contents underfoot while being read. One Backup#Approaches to backing up live data, approach to safely backin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Snapper Root List Screenshot
Snapper(s) may refer to: Animals * Lutjanidae, a family of fish known as snappers **''Lutjanus campechanus'', a fish found in the Gulf of Mexico and the Atlantic coast of the United States ** Bigeye snapper (''Lutjanus lutjanus''), a fish that primarily lives in the Pacific and Indian Oceans, sometimes known as simply "Snapper" ** Cubera snapper (''Lutjanus cyanopterus''), native to the western Atlantic Ocean * Fishes from other families including: ** Australasian snapper, ''Pagrus auratus'', also known as silver seabream ** Eastern nannygai, also known as red snapper, ''Centroberyx affinis'' ** Bluefish (''Pomatomus saltatrix''), of which the smallest are often known as "snappers" **''Sebastes'', some species of which are known as "Pacific snapper" or "red snapper" * Chelydridae, a family of freshwater turtles of which both extant species are known as snapping turtles, informally shortened to "snapper" ** Common snapping turtle ** Alligator snapping turtle * ''Sistrurus catenatus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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O'Reilly Media
O'Reilly Media, Inc. (formerly O'Reilly & Associates) is an American learning company established by Tim O'Reilly that provides technical and professional skills development courses via an online learning platform. O'Reilly also publishes books about programming and other technical content. Its distinctive brand features a woodcut of an animal on many of its book covers. The company was known as a popular tech conference organizer for more than 20 years before closing the live conferences arm of its business. Company Early days The company began in 1978 as a private consulting firm doing technical writing, based in the Cambridge, Massachusetts area. In 1984, it began to retain publishing rights on manuals created for Unix vendors. A few 70-page "Nutshell Handbooks" were well-received, but the focus remained on the consulting business until 1988. After a conference displaying O'Reilly's preliminary Xlib manuals attracted significant attention, the company began increas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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NTFS
NT File System (NTFS) (commonly called ''New Technology File System'') is a proprietary journaling file system developed by Microsoft in the 1990s. It was developed to overcome scalability, security and other limitations with File Allocation Table, FAT. NTFS adds several features that File Allocation Table, FAT and HPFS (file system), HPFS lack, including: access control lists (ACLs); filesystem encryption; transparent compression; sparse files; Journaling file system, file system journaling and shadow copy, volume shadow copy, a feature that allows backups of a system while in use. Starting with Windows NT 3.1, it is the default file system of the Windows NT family superseding the File Allocation Table (FAT) file system. NTFS read/write support is available on Linux and Berkeley Software Distribution, BSD using NTFS3 in Linux kernel, Linux and NTFS-3G in BSD. NTFS uses several files hidden from the user to store metadata about other files stored on the drive which can help impr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Unix File System
The Unix file system (UFS) is a family of file systems supported by many Unix and Unix-like operating systems. It is a distant descendant of the original filesystem used by Version 7 Unix. Design A UFS volume is composed of the following parts: * A few blocks at the beginning of the partition reserved for boot blocks (which must be initialized separately from the filesystem) * A superblock, containing a magic number identifying this as a UFS filesystem, and some other vital numbers describing this filesystem's geometry and statistics and behavioral tuning parameters * A collection of cylinder groups. Each cylinder group has the following components: ** A backup copy of the superblock ** A cylinder group header, with statistics, free lists, etc., about this cylinder group, similar to those in the superblock ** A number of inodes, each containing file attributes ** A number of data blocks Inodes are numbered sequentially, starting at 0. Inode 0 is reserved for unalloc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Namespace
In computing, a namespace is a set of signs (''names'') that are used to identify and refer to objects of various kinds. A namespace ensures that all of a given set of objects have unique names so that they can be easily identified. Namespaces are commonly structured as hierarchies to allow reuse of names in different contexts. As an analogy, consider a system of naming of people where each person has a given name, as well as a family name shared with their relatives. If the first names of family members are unique only within each family, then each person can be uniquely identified by the combination of first name and family name; there is only one Jane Doe, though there may be many Janes. Within the namespace of the Doe family, just "Jane" suffices to unambiguously designate this person, while within the "global" namespace of all people, the full name must be used. Prominent examples for namespaces include file systems, which assign names to files. Some programming languages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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ODS-5
Files-11 is the file system used in the RSX-11 and OpenVMS operating systems from Digital Equipment Corporation. It supports record-oriented I/O, remote network access, and file versioning. The original ODS-1 layer is a flat file system; the ODS-2 version is a hierarchical file system, with support for access control lists,. Files-11 is similar to, but significantly more advanced than, the file systems used in previous Digital Equipment Corporation operating systems such as TOPS-20 and RSTS/E. History The native OpenVMS file system is descended from older DEC operating systems and is similar in many ways, both having been designed by Dave Cutler. A major difference is the layout of directories. These file systems all provided some form of rudimentary non-hierarchical directory structure, typically based on assigning one directory per user account. Under RSTS/E, each user account was represented by two numbers, a 'project'',''programmer''/code> pair, and had one associated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Plan 9 From Bell Labs
Plan 9 from Bell Labs is a distributed operating system which originated from the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s and built on UNIX concepts first developed there in the late 1960s. Since 2000, Plan 9 has been free and open-source. The final official release was in early 2015. Under Plan 9, UNIX's '' everything is a file'' metaphor is extended via a pervasive network-centric filesystem, and the cursor-addressed, terminal-based I/O at the heart of UNIX-like operating systems is replaced by a windowing system and graphical user interface without cursor addressing, although rc, the Plan 9 shell, is text-based. The name ''Plan 9 from Bell Labs'' is a reference to the Ed Wood 1957 cult science fiction Z-movie '' Plan 9 from Outer Space''. The system continues to be used and developed by operating system researchers and hobbyists. History Plan 9 from Bell Labs was originally developed, starting in the late 1980s, by members of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Fossil (file System)
Fossil is the default file system in Plan 9 from Bell Labs. It serves the network protocol 9P and runs as a user space daemon, like most Plan 9 file servers. Fossil is different from most other file systems due to its snapshot/archival feature. It can take snapshots of the entire file system on command or automatically (at a user-set interval). These snapshots can be kept on the Fossil partition as long as disk space allows; if the partition fills up then old snapshots will be removed to free up disk space. A snapshot can also be saved permanently to Venti. Fossil and Venti are typically installed together. Features Important features include: *Snapshots are available to all users. No administrator intervention is needed to access old data. (This is possible because Fossil enforces file permissions; users can only access data which they would be allowed to access anyway; thus a user cannot snoop on another's old files or look at old passwords or such.) *Data in perma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Write Anywhere File Layout
The Write Anywhere File Layout (WAFL) is a proprietary file system that supports large, high-performance Redundant array of independent disks, RAID arrays, quick restarts without lengthy consistency checks in the event of a Crash (computing), crash or power failure, and growing the filesystems size quickly. It was designed by NetApp for use in its storage appliances like NetApp FAS, NetApp FAS, AFF, ONTAP#Cloud Volumes ONTAP, Cloud Volumes ONTAP and ONTAP#ONTAP Select, ONTAP Select. Its author claims that WAFL is not a file system, although it includes one. It tracks changes similarly to journaling file systems as logs (known as NVLOGs) in dedicated memory storage device non-volatile random access memory, referred to as NVRAM or NVMEM. WAFL provides mechanisms that enable a variety of file systems and technologies that want to access Block (data storage), disk blocks. Design WAFL stores metadata, as well as data, in files; metadata, such as inodes and block maps indicating wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Logical Volume Manager (Linux)
In Linux, Logical Volume Manager (LVM) is a device mapper framework that provides logical volume management for the Linux kernel. Most modern Linux distributions are LVM-aware to the point of being able to have their root file systems on a logical volume. Heinz Mauelshagen wrote the original LVM code in 1998, when he was working at Sistina Software, taking its primary design guidelines from the HP-UX's volume manager. Uses LVM is used for the following purposes: * Creating single logical volumes of multiple physical volumes or entire hard disks (somewhat similar to RAID 0, but more similar to JBOD), allowing for dynamic volume resizing. * Managing large hard disk farms by allowing disks to be added and replaced without downtime or service disruption, in combination with hot swapping. * On small systems (like a desktop), instead of having to estimate at installation time how big a partition might need to be, LVM allows filesystems to be easily resized as needed. * Performing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Block Device
In Unix-like operating systems, a device file, device node, or special file is an interface to a device driver that appears in a file system as if it were an ordinary file. There are also special files in DOS, OS/2, and Windows. These special files allow an application program to interact with a device by using its device driver via standard input/output system calls. Using standard system calls simplifies many programming tasks, and leads to consistent user-space I/O mechanisms regardless of device features and functions. Overview Device files usually provide simple interfaces to standard devices (such as printers and serial ports), but can also be used to access specific unique resources on those devices, such as disk partitions. Additionally, device files are useful for accessing system resources that have no connection with any actual device, such as data sinks and random number generators. There are two general kinds of device files in Unix-like operating systems, k ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Copy-on-write
Copy-on-write (COW), also called implicit sharing or shadowing, is a resource-management technique used in programming to manage shared data efficiently. Instead of copying data right away when multiple programs use it, the same data is shared between programs until one tries to modify it. If no changes are made, no private copy is created, saving resources. A copy is only made when needed, ensuring each program has its own version when modifications occur. This technique is commonly applied to memory, files, and data structures. In virtual memory management Copy-on-write finds its main use in operating systems, sharing the physical memory of computers running multiple processes, in the implementation of the fork() system call. Typically, the new process does not modify any memory and immediately executes a new process, replacing the address space entirely. It would waste processor time and memory to copy all of the old process's memory during the fork only to immediately dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |