If you have a mirror (even on the same disk) and your tsm goes down
dirty you have much better chances that your database will not get
corrupted.
TSM writes first to one db volume, when this commit is succesfull it
writes to the mirrored volume. When the tsm server crashes only one
volume will get corrupted. (the one it was writing to)  If you only have
one volume the above is not possible, and your db will get corrupted.
This means you will have to restore your DB.

Same goes for your log volumes.

regards

Paul Fielding wrote:

I don't see the value in mirroring the db and logs if they're placed on
Shark disk.   The purpose of TSM's mirroring is to provide disk
redundancy
in case of disk failure.   However, the Shark provides it for you.
Why add
the extra overhead of software mirroring when the hardware does a valiant
job in the background. The Quck Start recommendation doesn't take into
account that your disk is already protected...

regards,

Paul

----- Original Message -----
From: "Jones, Eric J" <eric.j.jones AT LMCO DOT COM>
To: <ADSM-L AT VM.MARIST DOT EDU>
Sent: Wednesday, April 06, 2005 2:56 PM
Subject: [ADSM-L] Question on SETUP

Good Afternoon.
I was asked to setup a new TSM server 5.2.2 on a AIX 5.2 server.
My question has to do with setting up the DB, LOG and DISKPOOL.
On our current servers which run the same O/S and TSM version the DB,
LOG
and DISKPOOL are mirrored.
On the new system I'm setting up these are all going to reside on a IBM
SAN(SHARK) which is all RAID.
Is there any reason to mirror them since the mirror would be on the same
set of drives(space was already allocated on a LUN)?
I understand it's always good to mirror(protect DB, LOG, DISKPOOL)
but in
this case I'd have to mirror to the same set of disk since I was only
allocated a set of space to work.  In the TSM class it also recommended
that you mirror for protection.
I'm in the middle of reading the "Quick Start" for the second time and I
see they recommend "Mirror your Database and recovery log for "Server
and
storage pool protection".  I wanted to make sure there was not a
performance issue or anything else.

Have a Great Day,
Eric Jones

*  eric.j.jones AT lmco DOT com
*:   607-751-4133

Cell : 607-972-7621

--
Otto Schakenbos
System Administrator

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