Problem:
When trying to create a snapshot, the following error message is logged:
Handler call failed: [...] failed to create snapshot pair [...]
Block storage has a limit of 1024 snapshots per LDEV. When this limit is reached, no more snapshots can be created.
Solution:
Review the RPO and Retention you have specified. If you set an overly aggressive RPO combined with long retention times then the snapshot limit can easily be breached.