You are gonna get soooooo many different answers to this question. And as
you said, everybody's situation is different.
In my opinion it depends on your need for speed.
-I have one TSM server that isn't stressed at all (in terms of GB per day it
has to process). Everything - DB, logs, stgpool vols, etc. is in one big
RAID array and that works just fine.
-I have another TSM server on a different network that runs flat out 24
hours per day.
On that server I had to give up RAID and mirror the log on 2 non-RAID SSA
disks to get enough speed to survive.
-YOu need more speed if you are in ROLLFORWARD mode than in NORMAL mode.
Re the volume sizes, guess what, "IT DEPENDS" on your situation.
If you only have a 6 GB data base, then three 2GB volumes will work nicely.
If you have a 30 GB data base, managing 15 different 2GB volumes gets
annoying.
And in the case of storage pool volumes, if you have multiple clients
backing up to multiple stgpool volumes in a disk pool, TSM will start
multiple I/Os - one to each volume, I think. So if you have 36 2GB volumes
on a 72 GB disk, TSm could in theory start 32 I/Os to that physical disk,
and THEN you will start to slow down due to head thrashing because you'll be
causing your own device contention.
SO, create as many stgpool volumes as you want concurrent I/O's to them,
assuming you are backing up a significant number of clients.
(If you are only backing up 3 big clients serially instead of doing 30
concurrently, you will see different results, anyway.)
The nice thing with TSM, if you set this stuff up and decide to change it
later, TSM makes it remarkably easy to do so!
Then pretty much ANY WAY YOU SET IT UP will work fine until you hit a
performance issue, then you can figure out how to work around those.
GOod luck!!
-----Original Message-----
From: Varney, Patrick [mailto:PAV5 AT PGE DOT COM]
Sent: Monday, September 30, 2002 3:22 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: TSM Database Disk Layout Recommendations
Hello All,
I'm sure that this general question has been asked many times, but every
situation is different. And I can't seem to get to the www.adsm.org site, so
here goes.
We just received some new SSA disks for our TSM servers and I'm looking for
some advice on the best way to lay everything out. Here are the details on
our planned environment (the SSA configuration has not been done yet, so
it's flexible):
Server:
RS/6000 7026-H70
4-way processor
4GB memory
1 SSA HBA (2 loops)
AIX 4.3.3 ML 10
TSM 4.2.2.12
Internal SCSI Storage:
4 x 9GB (current TSM database/log location)
SSA Loop 1:
8 x 9GB
RAID 5
Approx. 60GB
SSA Loop 2:
8 x 72GB
RAID 5
Approx. 500GB
TSM Database: Less than 30GB
TSM Log: 3-4GB
Disk Storage Pools: 300GB
My current plan is to put the TSM database on the 9GB SSA drives (using RAID
5, no TSM mirroring), the disk storage pool volumes on the 72GB SSA drives,
and use the internal 9GB drives for database dumps to disk. However, I'm
open to suggestion. Specifically, I am looking for answers to the following:
- Where is the best place for the TSM database log volumes? And if they are
sharing space on the SSA disks, is there any advantage to creating a
separate file system (in general, is there any performance
advantage/disadvantage to multiple file systems on one SSA RAID array)?
- Is there any reason to NOT do RAID 5 on the SSA disks?
- For the database and disk storage volumes, is it better to create more
smaller (2GB) volumes or enable "large file" support and create fewer?
Any help would be greatly appreciated.
Thanks,
Patrick Varney
Pacific Gas & Electric Company
Fairfield Information Operations Center (FFIOC)
Enterprise Services Group (ESG), Senior Network Specialist
* internal 8-227-2823
* external 707-436-2823
* pager 707-288-1513
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