Just as an FYI, I would check with your EMC CE to make sure your
clariion has the latest firmware upgrade if you are using ATA disks with
raid5 - without going into details, does the term "data loss" sound like
a bad idea?.

-----Original Message-----
From: asr AT UFL DOT EDU [mailto:asr AT UFL DOT EDU] 
Sent: Saturday, February 12, 2005 11:21 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: I have a db and disk pool volume question.


==> On Fri, 11 Feb 2005 15:38:58 -0500, "Martinez, Matt"
<matt AT IDEXX DOT COM> said:

> I have an opportunity to redesign the disk pool and db layout of our 
> TSM Server , and I was wondering if my fellow TSMers can help me with 
> it. First things first our environment is as follows, TSM Version: 
> 5.1.7 soon to be 5.2.? on Win2k, the Disk the DB will be stored on 
> will be a RAID 5 Disk on a EMC CX700 array.

> My main question is can TSM read/write multiple streams to a single 
> Disk or DB vol?

Multiple backup streams to a DISK stgpool volume: Yes.

Multiple streams to a DB vol: not well formed question: there aren't
streams of data hitting the DB vols.

I suggest you hit the archives for some of the older discussions about
optimization points for DB volumes.  My own solution to these has been
to deploy a large number of relatively slow spindles for DB, and some
very fast disk for recovery log, but that's a completely different
hardware regime.


> The reason I would do this is to optimize the I/O across all the 
> spindles.


If you want to have large RAIDs (to minimize loss of space to parity
drives) then you might as well have large volumes as small.  While there
are multiple streams permitted to hit a DISK volume at a time, there's
only one thread of execution talking to a given volume at a time.  This
means that if you have two volumes in the same stgpool on the same RAID,
that you're going to engender some contention.

If you've only got one volume in the stgpool, then you've serialized on
the stgpool, which isn't so bad because you need to serialize on the
underlying RAID anyway.

To solve this on my own system, I've got my SSA chopped up into 5-disk
RAIDs, which I understand to be a performance sweet-spot for 36-G SSA
disks.  Then every DISK pool I've got has a volume on each RAID.  It's
really kind of cool to watch a high-throughput session run, because you
can see a throughput spike drift from RAID to RAID as the incoming
session round-robins through the available disk volumes.


- Allen S. Rout