Allen S. Rout wrote:

I'm getting ready to define a set of disk storage volumes for my ADSM
setup,
with the intent that I would be using them as a more-or-less "landing pad";
i.e. they can accept data more efficiently than the optical or tape, and I
can
run more simultaneous sessions against them, but I don't really plan to
keep
data on them for long:  my nightly incrementals might regularly exceed the
size of the disk pool.

Someone here noted today "but that might cause migration, which I would
want
to avoid during the backup window".  Is there a reason to avoid that,
_other_
than simply losing access to the migrating volume during the migration
period?

Is this a dumb idea for some other reason?  I plan to have rather a lot of
fairly small spindles for disk pool: I won't lose a lot if a few of them go
into migration during a session, and I can migrate _all_ the data off
gradually during the day, so I can have a clean slate for the next night.

Any input, or references to Fine Manuals that I might Read, would be
welcome.

-Allen S. Rout
Allen,
Allen,

You do NOT want your disk pool to migrate to your tape pool during
migration.  ADSM does not perform well when system processes such as
migration are run concurrently with backup tasks.  I used to think that
this recommendation was a hold-over from MVS DFHSM storage management and
did not apply to ADSM.  I was wrong.  Backup performance and throughput are
significantly impacted if migration occurs during the backup window.  This
effect is magnified if you are using a multi-processor system since it
generates more locks.  I am working with a customer that was running an
RS/6000 R40 4-way server at 100% from 8pm to 6am.  We were able to reduce
utilization significantly below 100% by simply allocating disk pools large
enough to handle one night's backups and archives.  This enabled us to add
more clients without buying new hardware.  I hope this was helpful

DanC
=============================================
Daniel G. Crouse
IBM Certified Specialist - ADSM
Mainstar Software Corporation
Storage and Recovery Solutions
  URL:  www.mainstar.com
Email:  Dan.Crouse AT mainstar DOT com
Vmail:  800-233-6838
Voice:  770-682-7655
   Fax:  770-682-7739
=============================================