A point-in-time snapshot is a copy of a storage volume, file or database as they appeared at a given point in time and are used as method of data protection. In the event of a failure, users can restore their data from the most recent snapshot before the failure.
Many point-in-time snapshots are read-only. There are two main methods of keeping point-in-time snapshots up to date with changes:
- Pointer remapping -- When new copies of a point-in-time snapshot are made, the more recent copy will maintain a mapping to the original copy.
- Copy-on-write -- When changes are made to data, only the data that is modified will be copied again, rather than make another full copy of the data set.
Point-in-time snapshots are beneficial because a user can select a specific time they want to restore data from.