System: OES-NW SP3

I make regular pool snapshots of an NSS pool named DAT, which contains
three volumes. The snapshot store-on pool is BAK, on the same server.

Twice now, I have had all the pool snapshots of DAT simply disappear. No
warning, no error messages.

For example: Yesterday I created the snapshot DAT_WED3. I then verified it
by bringing it online, mounting the volumes, accessing some files etc.
After taking the snapshot offline again, it still showed normally (in
iManager) in the list of four or five snapshots of DAT.

This morning all the snapshots were gone.

Has anyone experienced or heard of such a thing?