Snapshot (Computer Storage)

Inhalt "Snapshot (Computer Storage)":

High Quality Content by WIKIPEDIA articles! 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 from a directory that has not yet been backed up into a directory that has already been backed up, then that file would be completely missing on the backup media. 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 stopping the accessing applications or by using the locking API provided by the operating system to enforce exclusive read access.