How very keen of you to have anticipated that!!  You are absolutely correct,
and the situation does occur at least once during each copy session.  A
"DUTxxx" message is issued when this occurs and the operator is responsible for
finding an output tape that has equal or longer length than the input tape.
It's basically trial & error but they usually find one after a couple of
tries.  Since it is a COMPLETELY manual process, it is error-prone and we do
followup checking to make sure nothing is missed.    It would be nice if ADSM
provided a 'fill the tape x%' parameter like DFHSM has.

It's the fastest method of copying tapes we have tried so this is one of the
difficulties we put up with.


In the previous Memo, dated, 02-17-97 01:47:47 PM, tom @ STAFF.UDC.UPENN.EDU
(Tom Denier) @ MGICSMTP wrote:

Mary Vollmer wrote:
> We have implemented our own method of creating tapes for disaster recovery.
We
> have  tape collocation turned on by node.  Day 1 of the week is Sunday night.
> On that night we start a new tape for each node by marking all tapes in the
> pool read-only on Sunday morning.  We run the incremental backups each night
> for the rest of the week.  Our server is MVS and we use CA1 as our tape
> management system.  Using CA1, we are able to find all the tapes that were
> created by ADSM since the last 'cut off' (Sunday morning).  We then use MVS
> DITTO to copy these tapes.  The internal tape label of the primary and
disaster
> recovery tapes are identical but the external label of the disaster recovery
> tapes has a different 1st number.  The rotation of these tapes is handled by
> CA1 by manually (via program, of course) setting vault codes, etc.  In our
> disaster tests, when ADSM calls for a 5xxxxx tape, we mount the 6xxxxx copy of
> that tape.  Because the internal label is 5xxxxx, it works just fine.
> Tuesday-Friday we select tapes from ADSM with utilization (not % reclamable)
of
> 15% or less and stack that data (using move data commands) on to that week's
> active tape for that node in an attempt to consolidate the data on the fewest
> possible tapes.  If you would like more detailed information about this
> process, I would be happy to share it.

As I understand the matter, two tape volumes of a given type will almost
always have slightly different capacities because of manufacturing
tolerances. How does the process described above avoid problems caused
by DITTO output volumes that have slightly smaller capacities than the
corresponding input volumes?