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Differential Backup
A differential backup is a type of data backup that preserves data, saving only the difference in the data since the last full backup. The rationale in this is that, since changes to data are generally few compared to the entire amount of data in the data repository, the amount of time required to complete the backup will be smaller than if a full backup was performed every time that the organization or data owner wishes to back up changes since the last full backup. Another advantage, at least as compared to the incremental backup method of data backup, is that at data restoration time, at most two backup media are ever needed to restore all the data. This simplifies data restores as well as increases the likelihood of shortening data restoration time. Meaning A differential backup is a cumulative backup of ''all'' changes made since the last ''full'' backup, i.e., the ''differences'' since the last full backup. The advantage to this is the quicker recovery time, requiring only a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Backup
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is " back up", whereas the noun and adjective form is "backup". Backups can be used to recover data after its loss from data deletion or corruption, or to recover data from an earlier time. Backups provide a simple form of disaster recovery; however not all backup systems are able to reconstitute a computer system or other complex configuration such as a computer cluster, active directory server, or database server. A backup system contains at least one copy of all data considered worth saving. The data storage requirements can be large. An information repository model may be used to provide structure to this storage. There are different types of data storage devices used for copying backups of data that is already in secondary storage onto archi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Full Backup
In information technology, a backup, or data backup is a copy of computer data taken and stored elsewhere so that it may be used to restore the original after a data loss event. The verb form, referring to the process of doing so, is "back up", whereas the noun and adjective form is " backup". Backups can be used to recover data after its loss from data deletion or corruption, or to recover data from an earlier time. Backups provide a simple form of disaster recovery; however not all backup systems are able to reconstitute a computer system or other complex configuration such as a computer cluster, active directory server, or database server. A backup system contains at least one copy of all data considered worth saving. The data storage requirements can be large. An information repository model may be used to provide structure to this storage. There are different types of data storage devices used for copying backups of data that is already in secondary storage onto archive file ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Incremental Backup
An incremental backup is one in which successive copies of the data contain only the portion that has changed since the preceding backup copy was made. When a full recovery is needed, the restoration process would need the last full backup plus all the incremental backups until the point of restoration. Incremental backups are often desirable as they reduce storage space usage, and are quicker to perform than differential backups. Variants Incremental The most basic form of incremental backup consists of identifying, recording and thus, preserving only those files that have changed since the last backup. Since changes are typically low, incremental backups are much smaller and quicker than full backups. For instance, following a full backup on Friday, a Monday backup will contain only those files that changed since Friday. A Tuesday backup contains only those files that changed since Monday, and so on. A full restoration of data will naturally be slower, since all increments mu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Backup Rotation Scheme
A backup rotation scheme is a system of backing up data to computer media (such as tapes) that minimizes, by re-use, the number of media used. The scheme determines how and when each piece of removable storage is used for a backup job and how long it is retained once it has backup data stored on it. Different techniques have evolved over time to balance data retention and restoration needs with the cost of extra data storage media. Such a scheme can be quite complicated if it takes incremental backups, multiple retention periods, and off-site storage into consideration. Schemes First in, first out A first in, first out (FIFO) backup scheme saves new or modified files onto the "oldest" media in the set, i.e. the media that contain the oldest and thus least useful previously backed up data. Performing a daily backup onto a set of 14 media, the backup depth would be 14 days. Each day, the oldest media would be inserted when performing the backup. This is the simplest rotation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Oracle Corporation
Oracle Corporation is an American multinational computer technology corporation headquartered in Austin, Texas. In 2020, Oracle was the third-largest software company in the world by revenue and market capitalization. The company sells database software and technology (particularly its own brands), cloud engineered systems, and enterprise software products, such as enterprise resource planning (ERP) software, human capital management (HCM) software, customer relationship management (CRM) software (also known as customer experience), enterprise performance management (EPM) software, and supply chain management (SCM) software. History Larry Ellison co-founded Oracle Corporation in 1977 with Bob Miner and Ed Oates under the name Software Development Laboratories (SDL). Ellison took inspiration from the 1970 paper written by Edgar F. Codd on relational database management systems ( RDBMS) named "A Relational Model of Data for Large Shared Data Banks." He heard about t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Continuous Data Protection
Continuous data protection (CDP), also called continuous backup or real-time backup, refers to backup of computer data by automatically saving a copy of every change made to that data, essentially capturing every version of the data that the user saves. In its true form it allows the user or administrator to restore data to any point in time. The technique was patented by British entrepreneur Pete Malcolm in 1989 as "a backup system in which a ''copy'' ditor's emphasisof every change made to a storage medium ''is recorded as the change occurs'' ditor's emphasis" In an ''ideal'' case of ''continuous data protection'', the recovery point objective—"the maximum targeted period in which data (transactions) might be lost from an IT service due to a major incident"—is zero, even though the recovery time objective—"the targeted duration of time and a service level within which a business process must be restored after a disaster (or disruption) in order to avoid unacceptabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Delta Encoding
Delta encoding is a way of storing or transmitting data in the form of '' differences'' (deltas) between sequential data rather than complete files; more generally this is known as data differencing. Delta encoding is sometimes called delta compression, particularly where archival histories of changes are required (e.g., in revision control software). The differences are recorded in discrete files called "deltas" or "diffs". In situations where differences are small – for example, the change of a few words in a large document or the change of a few records in a large table – delta encoding greatly reduces data redundancy. Collections of unique deltas are substantially more space-efficient than their non-encoded equivalents. From a logical point of view the difference between two data values is the information required to obtain one value from the other – see relative entropy. The difference between identical values (under some equivalence) is often called ''0'' or the neut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Dar (disk Archiver)
dar (disk archive) is a computer program, a command-line archiving tool intended as a replacement for tar in Unix-like operating systems. Features * Support for slices, archives split over multiple files of a particular size * Option of deleting files from the system which are removed in the archive * Full backup * Differential backup * Incremental backup, * Decremental backup * Takes care of any type of inode (directory, plain files, symlinks, special devices, named pipes, sockets, doors, ...) * Takes care of hard-linked inodes (hard-linked plain files, char devices, block devices, hard-linked symlinks) * Takes care of sparse files * Takes care of Linux file Extended Attributes, * Takes care of Linux file ACL * Takes care of Mac OS X file forks * Takes care of some filesystem specific attributes like Birthdate of HFS+ filesystem and immutable, data-journaling, secure-deletion, no-tail-merging, undeletable, noatime attributes of ext2/3/4 filesystem. * Per-file co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Dump (Unix)
The dump command is a program on Unix and Unix-like operating systems used to back up file systems. It operates on blocks, below filesystem abstractions such as files and directories. Dump can back up a file system to a tape or another disk. It is often used across a network by piping its output through bzip2 then SSH. A dump utility first appeared in Version 6 AT&T UNIX. A dump command is also part of ASCII's ''MSX-DOS2 Tools'' for MSX-DOS version 2. Usage dump 0123456789acLnSuB records b blocksizeC cachesize D dumpdates d density -P pipecommand h level s feetT datefilesystem $ dump -W , -w See also *restore (program) *tar (file format) *cpio *rsync rsync is a utility for efficiently transferring and synchronizing files between a computer and a storage drive and across networked computers by comparing the modification times and sizes of files. It is commonly found on Unix-like operatin ... References External linksHome page of the Linux Ext2 filesystem d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rsync
rsync is a utility for efficiently transferring and synchronizing files between a computer and a storage drive and across networked computers by comparing the modification times and sizes of files. It is commonly found on Unix-like operating systems and is under the GPL-3.0-or-later license. Rsync is written in C as a single threaded application. The rsync algorithm is a type of delta encoding, and is used for minimizing network usage. Zlib may be used for additional data compression, and SSH or stunnel can be used for security. Rsync is typically used for synchronizing files and directories between two different systems. For example, if the command rsync local-file user@remote-host:remote-file is run, rsync will use SSH to connect as user to remote-host. Once connected, it will invoke the remote host's rsync and then the two programs will determine what parts of the local file need to be transferred so that the remote file matches the local one. One application of r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Data Synchronization
Data synchronization is the process of establishing consistency between source and target data stores, and the continuous harmonization of the data over time. It is fundamental to a wide variety of applications, including file synchronization and mobile device synchronization. Data synchronization can also be useful in encryption for synchronizing public key servers. File-based solutions There are tools available for file synchronization, version control (CVS, Subversion, etc.), distributed filesystems ( Coda, etc.), and mirroring (rsync, etc.), in that all these attempt to keep sets of files synchronized. However, only version control and file synchronization tools can deal with modifications to more than one copy of the files. * File synchronization is commonly used for home backups on external hard drives or updating for transport on USB flash drives. The automatic process prevents copying already identical files, thus can save considerable time relative to a manual copy, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Incremental Computing
Incremental computing, also known as incremental computation, is a software feature which, whenever a piece of data changes, attempts to save time by only recomputing those outputs which depend on the changed data. When incremental computing is successful, it can be significantly faster than computing new outputs naively. For example, a spreadsheet software package might use incremental computation in its recalculation feature, to update only those cells containing formulas which depend (directly or indirectly) on the changed cells. When incremental computing is implemented by a tool that can implement it for a variety of different pieces of code automatically, that tool is an example of a program analysis tool for optimization. Static versus dynamic Incremental computing techniques can be broadly separated into two types of approaches: ''Static approaches'' attempt to derive an incremental program from a conventional program P using, e.g., either manual design and refactor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |