Your best bet is to use schedmode polling and let TSM/ADSM spread the load.
This is the easiest.  Yes, in order to have immediate action things happen
you will need prompted mode, but how often do you do that?

Polling works as follows: each client in this schedule mode associated with
the schedule will periodically poll the server asking if there is anything
to do.  If there is, the server will provided the client a random start time
within the first half of the schedule window.  The client will then start
the backup at that time.  Each client is assigned a different time.  In this
fashion, your 15 clients will start sometime within the first half of the
window and will be reasonably randomized.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80949-1313
(719) 531-5926
Fax: (719) 260-5991
Email: lipp AT storsol DOT com
www.storsol.com
www.storserver.com