We are not there yet but I will be in the same situation.  I was going to group
my clients by size with a maximum of 10 clients per group.  I was then going to
set up a storage group for each client group and continue to let ADSM pull
scratch tapes as needed in each storage group.  Collocation would be turned
off.  After the change we would, in effect, be collocating by client group
instead of by individual node.  The number of tapes used by each client group
would still be relatively low because the capacity of the tape is so much
higher.  The number of tape mounts for a large restore would still be low.   We
have some extremely large clients that may end up as the only client in the
'group'.


In the previous Memo, dated, 05-06-97 10:45:25 AM, PrathW1 @
CENTRAL.SSD.JHUAPL.EDU ("Prather, Wanda") @ MGICSMTP wrote:

We have an automated tape library.
I just check in tape cartridges in "scratch" status, and let ADSM pull
tapes as needed from the scratch pool into the backup and archive tape
pools.
My backup tape pool is colocated.
This works fine because I have more cartridges than clients.

But, we are about to add hundreds of clients, so that I will have more
clients than cartridges.
Each cartridge holds 35 GB, so I should be able to get several clients
per cartridge with no problem, but I would still like to colocate for
speed on restore..

How do other people handle this situation?
I think that probably all I have to do is stop using "scratch" tapes and
manually define a fixed number of cartidge volumes to each pool.  Are
there other considerations?