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Oak snapshot feature

Feature description

Snapshots provide point-in-time copies to which is it possible to roll back. Once the optional feature is enabled on Oak for a group, the (read-only) snapshots are directly accessible at $OAK/.snapshot/ which is similar to $PI_HOME/.snapshot/ on the Sherlock Isilon. 

However, this feature does NOT provide a copy of the data in case of disaster, as the snapshot resides on the same /oak filesystem. Even with snapshot enabled, we do recommend to have important data replicated to another storage system.

The snapshot technology available on Oak is based on both clone and incremental snapshots using an open source tool named rsnapshot, itself based on the rsync tool. Unlike Copy-On-Write (COW) snapshot, the original “clone” snapshot requires as much storage capacity as the original data, then incremental snapshots are used. In that sense, the technology used is similar to Time Machine on macOS, but stored on the same filesystem.

Please note that the disk space used by rsnapshot will be accounted in your group volume quota. This additional space depends on the usage you make of Oak and might be difficult to estimate. If you choose to enable the rsnapshot option, please take that into account and don't hesitate to ask for more storage space. When the snapshot feature is enabled, your personalized usage dashboard will display the amount of disk space used by the snapshots.

 

How to enable snapshots on Oak?

Please contact us at srcc-support@stanford.edu.