PowerScale OneFS 9.8.0.0 Web Administration Guide

Best practices for creating snapshots

Consider the following snapshot best practices when working with a large number of snapshots.

It is recommended that you do not create more than 1,000 snapshots of a single directory to avoid performance degradation. If you create a snapshot of a root directory, that snapshot counts towards the total number of snapshots for any subdirectories of the root directory. For example, if you create 500 snapshots of /ifs/data and 500 snapshots of /ifs/data/media, you have created 1,000 snapshots of /ifs/data/media. Avoid creating snapshots of directories that are already referenced by other snapshots.

It is recommended that you do not create more than 1,000 hard links per file in a snapshot to avoid performance degradation. Always attempt to keep directory paths as shallow as possible. The deeper the depth of directories referenced by snapshots, the greater the performance degradation.

Creating snapshots of directories higher on a directory tree will increase the amount of time it takes to modify the data referenced by the snapshot and require more cluster resources to manage the snapshot and the directory. However, creating snapshots of directories lower on directories trees will require more snapshot schedules, which can be difficult to manage. It is recommended that you do not create snapshots of /ifs or /ifs/data.

You can create up to 20,000 snapshots on a cluster at a time. If your workflow requires a large number of snapshots on a consistent basis, you might find that managing snapshots through the OneFS command-line interface is preferable to managing snapshots through the OneFS web administration Interface. In the CLI, you can apply a wide variety of sorting and filtering options and redirect lists into text files.

Mark snapshots for deletion when they are no longer needed, and ensure that the SnapshotDelete system job is enabled. Disabling the SnapshotDelete job prevents unused disk space from being recaptured and can also cause performance degradation over time.

If the system clock is set to a time zone other than Coordinated Universal Time (UTC), SnapShotIQ modifies snapshot duration periods to match Daylight Savings Time (DST). Upon entering DST, snapshot durations are increased by an hour to adhere to DST; when exiting DST, snapshot durations are decreased by an hour to adhere to standard time.