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Snapshot (computer Storage)
In computer systems, a snapshot is the state of a system at a particular point in time. The term was coined as an analogy to that in photography. It can refer to an actual copy of the state of a system or to a capability provided by certain systems. Rationale A full backup of a large data set may take a long time to complete. On 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 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 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 approach to safely backing up live data is to temporarily disable write access to data during t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 caten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File System Permissions
Most file systems include attributes of files and directories that control the ability of users to read, change, navigate, and execute the contents of the file system. In some cases, menu options or functions may be made visible or hidden depending on a user's permission level; this kind of user interface is referred to as permission-driven. Two types of permissions are widely available: traditional Unix file system permissions and access-control lists (ACLs) which are capable of more specific control. File system variations The original File Allocation Table file system has a per-file all-user read-only attribute. NTFS implemented in Microsoft Windows NT and its derivatives, use ACLs to provide a complex set of permissions. OpenVMS uses a permission scheme similar to that of Unix. There are four categories (system, owner, group, and world) and four types of access permissions (Read, Write, Execute and Delete). The categories are not mutually disjoint: World includes Group, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 unallocated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
ODS-5
Files-11 is the file system used by Digital Equipment Corporation OpenVMS operating system, and also (in a simpler form) by the older RSX-11. It is a hierarchical file system, with support for access control lists, record-oriented I/O, remote network access, and file versioning. 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 directory. Special system files, such as program e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
