Joined: 14 Mar 2007 Posts: 8657 Location: Back in jolly old England
Not sure how universal this is...
HSM will take a backup after a dataset is modified. Issue:
HLIST DSN(my.seq) BOTH
And it will give you a rough estimate of when the last change was made.
Good avenue to explore. But ...... it does depend largely on the storage polices in place.
I have worked at some wierd places when it came to backup / recovery strategies. Some shops do not use HSM for production backups. Some perform backups daily.
Also, DFdss can be used as a backup and then reset the VTOC bit at end of backup.
I would suggest that the OP has a chat with the storage group and see what they can find out, and with any luck a result.
SMF records are not always accurate. A file may be opened for output (SMF type 15) but not actually written to. One of the reasons that many shops do a delete dataset at the start of the job, create the dataset in flight is to have accurate creation data.