Aggregate Snapshot reserve
Just as there is space reserved for volume Snapshot copies in their volume (the volume Snapshot reserve), there is space reserved for aggregate Snapshot copies in the aggregate. This space is called the aggregate Snapshot reserve. Usually, the default aggregate Snapshot reserve of 5 percent is sufficient. However, you might increase the aggregate Snapshot reserve under some circumstances.
The default size of the aggregate Snapshot reserve is 5 percent of the aggregate size. For example, if the size of your aggregate is 500 GB, then 25 GB is set aside for aggregate Snapshot copies.
Note: Unlike volume Snapshot copies, aggregate Snapshot copies cannot consume any space outside of their Snapshot reserve,
if automatic aggregate Snapshot copy deletion is enabled.
If automatic aggregate Snapshot copy deletion is disabled, then aggregate Snapshot copies can consume space outside of their Snapshot reserve.
You should consider increasing the aggregate Snapshot reserve if:
- You find that aggregate Snapshot copies are being created and deleted often enough to affect system performance.
- You need to complete a mirror resync when an aggregate is being written to very frequently. In this case, the default aggregate Snapshot reserve may not be large enough to hold all the resync Snapshot copies until the resync completes.
For information about how your system is using space reserved for aggregates, including aggregate Snapshot copies, use the aggr show_space command. See the na_aggr(1) man page for detailed information.
Note: If you have automatic aggregate Snapshot copy creation enabled, you should not decrease the size of the aggregate Snapshot reserve below the default of 5 percent. If you need to reclaim the space being used for the aggregate Snapshot reserve, disable automatic aggregate Snapshot copy creation.
