Best practices for creating snapshot schedules

Snapshot schedule configurations can be 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 approximately twice as long 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 versus ordered deletions depend on how often the data referenced by the snapshots is modified. If the data is modified frequently, unordered deletions will 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 can be 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 at the same time when possible.

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

Table 1. Snapshot schedule configurations
Deletion type
Snapshot frequency
Snapshot time
Snapshot expiration
Max snapshots retained
Ordered deletion (for mostly static data)
Every hour
Beginning at 12:00 AM Ending at 11:59 AM
1 month
720
Unordered deletion (for frequently modified data)
Every other hour
Beginning at 12:00 AM Ending at 11:59 PM
1 day
27
Every day
At 12:00 AM
1 week
Every week
Saturday at 12:00 AM
1 month
Every month
The first Saturday of the month at 12:00 AM
3 months