Your customer complains about missing volume snapshot copies on a SnapMlrror destination.

= When a SnapMirror resync operation is performed, the destination volume is reverted to the most recent common snapshot copy with the source volume. Any newer snapshot copies that exist on the destination volume are deleted automatically, unless they are marked as busy or locked. This is done to ensure that the destination volume is consistent with the source volume and to avoid data loss or corruption. Therefore, if the customer complains about missing snapshot copies on the destination volume after a SnapMirror resync, the most likely cause is that those snapshot copies were newer than the common snapshot that was chosen for resync and were removed automatically by the system. References = SnapMirror resync operation, SnapMirror resync or update failed No Snapshot copies found on volume, Even though there is common snapshot, SnapMirror resync fails with error: No common snapshot copy found between source and destination volume