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.
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 ...
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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.
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 the backup, either by...
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