You should consider increasing the aggregate Snapshot reserve under some circumstances.
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.
As more and more data blocks in the aggregate are changed, the aggregate Snapshot reserve gradually becomes full. Data ONTAP automatically deletes the oldest aggregate Snapshot copies to recover space in the aggregate Snapshot reserve.
Newly created nonmirrored aggregates, including the root aggregate, have the aggregate Snapshot reserve set to 0 percent by default. A newly created mirrored aggregate's Snapshot reserve is set to 5 percent by default.
If you convert an existing, nonmirrored aggregate to a mirrored aggregate, the system attempts to increase the aggregate Snapshot reserve to 5 percent. If there is not enough space in the aggregate for the reserve increase, the operation to convert a nonmirrored aggregate to a mirrored aggregate fails.
You should consider increasing the aggregate Snapshot reserve in the following situations:
In this case, the standard aggregate Snapshot reserve size of 5 percent might not be large enough to hold all the resynchronized Snapshot copies until the resync operation is complete.
To preserve aggregate Snapshot copies, you would increase the reserve sufficiently to keep the aggregate Snapshot copies available for overwrites until they are no longer needed and delete all other Snapshot copies.
If an aggregate has an aggregate Snapshot reserve of 0 percent, the operation to create aggregate Snapshot copies still succeeds if the aggregate has enough free space available.