Q:
What happens when the migration process starts on the diskpool. Do the
files stop getting backed up for the period the migration is taking
place or do the two processes happen concurrently( i.e backup to
diskpool and migration from diskpool)?.

A:
Backup will continue to the disk Storage Pool while Migration is running.
If the disk Storage Pool reaches 100% migratable then the backup will
directed to the next Pool in the hierarchy (usually the tape Pool).  If no
drives are available in the tape Pool (because they are being used for
migration) the backup will wait for a drive to become available.

Q:
If the former, is it better to use a very small diskpool, so in effect
the data streams almost directly to the tape device?

It's best to avoid backup and migration running concurrently as it will
usually cause much contention for disk resource and slow both backup and
migration.  If you have data that is large average file sizes from few
clients it is best to send it directly to tape.

David Daun, IBM Green Bay
ADSM Advanced Technical Support Center
920-756-9022 - djdaun AT us.ibm DOT com