PowerScale OneFS 9.8.0.0 Web Administration Guide

Best practices for creating snapshot schedules

Snapshot schedule configurations are categorized by how they delete snapshots: ordered deletions and unordered deletions.

An ordered deletion is the deletion of the oldest snapshot of a directory. An unordered deletion is the deletion of a snapshot that is not the oldest snapshot of a directory. Unordered deletions take longer to complete and consume more cluster resources than ordered deletions. However, unordered deletions can save space by retaining a smaller total number of snapshots.

The benefits of unordered deletions compared with ordered deletions depend on how often the data that is referenced by the snapshots is modified. If the data is modified frequently, unordered deletions save space. However, if data remains unmodified, unordered deletions will most likely not save space, and it is recommended that you perform ordered deletions to free cluster resources.

To implement ordered deletions, assign the same duration period for all snapshots of a directory. The snapshots are created by one or multiple snapshot schedules. Always ensure that no more than 1000 snapshots of a directory are created.

To implement unordered snapshot deletions, create several snapshot schedules for a single directory, and then assign different snapshot duration periods for each schedule. Ensure that all snapshots are created simultaneously when possible.

The following table describes snapshot schedules that follow snapshot best practices: