As long as your disk pool is large enough to hold a day's worth of data you
can do a

backup stg diskpool copypool

before you migrate the data (doesn't have to be before if you have cache=yes
on diskpool).  This way you get the data to the copypool and to the
tapepool.

If you have the situation where highmig was reached on diskpool before the
backup stg was issued, you won't have all of the data in the copypool.

Typically, with multi-drive systems we'll perform daily processing as
follows:

backup stg diskpool copypool
backup stg tapepool copypool  (to get any data that might have migrated)
update stg diskpool highmig=0 lowmig=0  (to perform migration)
backup db

There is all kinds of timing issues to get these things to happen correctly
and most efficiently.  Scripts have been written by many folks and there are
some third party products that handle the sequencing of these commands.
Worst case, set up admin schedules with sufficient time between them to
allow the processing to complete before starting the next step.

And first thing you do is go and buy another drive.  Single drive TSM
systems are a pain in the neck (or nether regions).

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80949-1313
(719) 531-5926
Fax: (240) 539-7175
Email: lipp AT storsol DOT com or lipp AT storserver DOT com
www.storsol.com
www.storserver.com