We have two hosts, FAS270 and FAS 2020. FAS 270 is using as filer and FAS2020 is using for snap mirroring(backup of FAS270). When I am trying to delete old snap shot from FAS 2020, it is showing the message "Snapshot operation not allowed on a read-only volume." How we can delete old snap shot???
SnapMirror mirrors everything from primary - including snapshots.
If you want to get rid of a particular snapshot, then you have to delete it from primary & that change will be reflected during the next SnapMirror update.
This is true for volume snapmirrors. You can delete local snapshots on qtree snapmirror destinations, just no the baselines of the snapmirror relationships.