What release of OS/390 are you on? If it's an older release without TCP
having been incorporated into the USS, then you will see a lot of
get/freemains. I had an issue that I actually got to talk to a developer
about and we had a nice discussion about lots of things. One of them being
where TSM can use the BPX socket calls instead of the standard TCP socket
calls. He said that the conversion under the covers from the TCP socket
calls to the BPX calls and back again was a BIG overhead. He said you could
see 40% or more of CPU reduction moving to native BPX. He said you probably
wouldn't see much throughput difference unless you were moving to the new
Gigabit OSA cards.

We have a TSM server running on  an LPAR on a 9672-R44 with OSA-2 Fast
Ethernet cards. The disk is IBM ESS with 8 CHPID's to each, but the Magstar
3590B's are a bottle neck, too. Actually, I think ESCON is a bottleneck at
only 15MB/sec. I see about a 10-12GB/hour backup throughput via the OSA-2's.
I see about 25GB/hour tape throughput. CPU during the backup window runs
high, but this is running on a test/dev LPAR so that's not much of an issue.

I would like to get off this platform because of the tape throughput issues.
We're starting to backup more data than I can process for COPYPOOLing in the
available time before the next backup window occurs. The TSM DB is 18GB at
about 70%. That backup takes almost an hour. Because of the amount of time
to backup and restore the TSM DB, we are thinking of a different approach.
Since we have an ESS and Flashcopy, we are concidering bring TSM down at the
point where we normally do the BACKUP DB and then using Flashcopy to create
full disk copies of the volumes where the DBVOLUMES reside. Then bring TSM
back up. With Flashcopy, this process should only take about 2-minutes. Then
the flashcopy volumes would be backed up to tape with DFDSS and sent
offsite.

Bill Boyer
DSS, Inc.