ADSM-L

ADSM task prioritization

1998-09-29 15:19:52
Subject: ADSM task prioritization
From: Cheri Howard <Cheri_Howard AT AAL DOT ORG>
Date: Tue, 29 Sep 1998 14:19:52 -0500
Last week, I posted the following question on listserv.  My thanks to David
Daun, IBM Green Bay
ADSM Advanced Technical Support Center, for sending the information that
follows my original question.  Hope this is of help to others!

**********************
Original question:

I'm wondering if the ADSM server gives priority to tasks that it is
running?  For example, does backup take priority over reclamation?  Does
restore take priority over migration?  etc., etc., etc.  And if it does
give priority, how is that done and what is the order of heirarchy?
We're running an ADSM MVS V2 server.
*********************
Dave's response:

Look in the ADSM V3 Administrators Guide in the Section "Managing Server
Processes" and the sub-section "Mount Point Preemption".  It's a rather
complicated mechanism but essentially there are two groups of ADSM tasks:
1)Tasks that can be preempted by other other tasks (in group 2) for a mount
point.  The tasks in this group are organized in priority order.  2) Tasks
that
do the preempting.   It's explained pretty well in the book.

ADSM does not favor one type of task over another with respect to CPU
resources.

Contention at ADSM's database is often the source of reduced performance
when you have multiple sessions/processes running concurrently.  The degree
to
which this occurs depends on which tasks are running together.  An ADSM
Database Backup can have a significant effect on other activity, for
example.
Many backup sessions running together usually don't suffer much from DB
contention.  If you want to get optimal restore peformance the best thing
you
can do is to minimize other activity at the ADSM Server.  Some other things
you
can try:
Check the Database Buffer pool cache hit percentage with a Q DB F=D
command.
If this value is less than 98%, add some pool space with the BUFFPOOLSIZE
parm
in the server options file (you'll have to restart the server)
Change the layout of the ADSM Database by spreading it across more DB
volume
and more physical disks.
If you are running concurrent backup tasks to disk Storage Pools, try
turning
Disk Storage Pool Caching OFF.  This will reduce the number of DB updates
as
the backups run.
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