From the course: Learning FreeNAS

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Snapshots

Snapshots

From the course: Learning FreeNAS

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Snapshots

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- [Instructor] A Snapshot is a read-only representation of an entire file system or data set at an exact moment in time. Snapshots can be created very quickly and they take up very little space to start out. As a live file system changes, a Snapshot protects blocks of data that would be modified and continues to point to the original data. This is made possible by the copy-on-write mechanism of ZFS. When we change anything on a ZFS volume, any data blocks that would be modified by a change aren't altered directly. Rather the change blocks are written out fully to empty space instead and the file system references those new blocks instead of the old ones. In normal operation, old, unused blocks then become available to be reclaimed or overwritten later. But with the Snapshot, the system protects those blocks and preserves them instead. Very little space is taken up when a Snapshot is created. But as files are deleted or changed,…

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