Kelly Lipp wrote:

It can be thought of as the "just in case" backup operation.  You may
well have had migrations.

I'm not sure if data that gets migrated, cached or not, is backed up
from disk or from tape.  I'm thinking that if it has been migrated and
is cached, the backup will occur from the nextstgpool in any event.
Perhaps an IBM dude can clear that up.  Or Mr. Sims.

Bingo. A colleague here had a similar idea, so I went looking for
something definitive in the documentation and found:

   In a random-access storage pool, neither cached copies of migrated
   files nor damaged primary files are backed up.

This is from the 5.3 Administrators' Reference under BACKUP STGPOOL.

I'm sure someone had a reason for making that design decision, but I
have no idea what it'd be.

Time to go rearrange the order of backups and migrations, I guess, or
just live with it.

Kelly J. Lipp

Nick