Dean,
Long time no hear! At least by me!
Traditionally, based on information provided at an IBM conference a
million years ago, we established that two volumes per physical drive is
perhaps osmium. Actually, the number supposedly is between two and
three. Something, as I recall, about getting sufficient TSM threads
going to cause a disk queue length thus assuring the bottleneck is the
I/O subsystem.
One other thing to consider/try is file device class rather than disk
device class. According to IBM, file device class is strategic, while
disk device class is not. This COULD mean (note I said could) that DISK
is going away sometime. I don't know about that, but file device class
has lots of nice and unique features.
You are in the perfect position to test some of this a report your
findings! Try three disk device volumes and observer the throughput.
Then try two, then try FILE, etc. I know, I know, if you had time to
play you wouldn't be a TSM administrator!
I've done some of this sort of testing (I'm not a TSM administrator so
have plenty of time...) and have not seen a significant difference.
One final thing: if I intend to migrate all of the data from the disk
based pools daily, I would not use RAID5 for these volumes. I know that
RAID5 does not perform well when you load it up with multiple
simultaneous writes so be careful about that. Unless you have large
writeback caches on your controllers...
Kelly J. Lipp
VP Manufacturing & CTO
STORServer, Inc.
485-B Elkton Drive
Colorado Springs, CO 80907
719-266-8777
lipp AT storserver DOT com
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Dean Winger
Sent: Friday, February 02, 2007 1:02 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: [ADSM-L] how many volumes per disk storagepool?
Help Please
It's been awhile since I have setup a TSM server for Windows (Tivoli
Storage Manager Enterprise Addition 5.4). I am trying to find out what
the optimum number of volumes I should define for each primary disk
storage pool.
I have a disk array that I broke into 3 Raid 5 groups; one group for
Daily backups, one for SQL backups, and one for Archives. I also have a
Raid 1 group defined for my DB backups and Log files.
The Raid 5 groups consist of three 300GB SAS drives each. What size and
how many volumes should I create for each Raid 5 group?
For the DB and Log files I have a 270GB Raid 1 group. My database is
currently around 40GB. What size should I make the DB and Log pools, and
how many volumes should each have?
Thanks so much
Dean
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