I've always been from the many spindles, small disks, JBOD, TSM s/w
mirror camp.
In the past, I have seen a DB performance increase, by moving the DB
architecture to the above configuration.

However, like many, I have watched the threads closely and I'm seriously
going to consider the RAID0 striping option with my next major
implementation. Not sure which way I will be going regards the mirroring
(H/W vs S/W). I've been involved in a DB corruption, caused by H/W
mirroring and coupled with the fact that the previous DB backup was
corrupt, it wasn't pretty. Conversely, I have been through a number of
'unscheduled' server downs, with TSM mirroring and never had a DB
corruption.

I have been experimenting with a Wintel server and an old Compaq FC RAID
array with 12 x 18GB disks and so far the RAID0 option is coming out on
top. I appreciate that it's Wintel and Compaq, but the T&R budget
doesn't stretch. It's certainly a step in the right direction, a Linux
TSM install & test will be my next move.

Leigh

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Allen S. Rout
Sent: 07 February 2006 03:26
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Database mirroring, again

>> On Mon, 6 Feb 2006 13:07:08 -0600, Roger Deschner <rogerd AT UIC DOT EDU>
said:

> Hardware 2x2 SSA RAID10 (2-way striped mirrored pairs), raw volumes, 4
> dbvols per virtual RAID volume (hdisk), which is still 2 dbvols per
real
> disk.

I think the number volumes/spindle is increasingly irrelevant in the
days of multi-GB caches in storage subsystems.  My SSA is one thing, a
sharkesque gizmo is quite another.


> There has been some discussion of relative database corruption risk
> with TSM mirroring versus hardware or OS mirroring. [...]

I've been feeling myself change opinion on this, recently.  The
reliable-storage level here is between the log and the db, no?  I
think I'll be experimenting with OS- or hardware-level protection the
next time we have a DB architecture question.  Tho, with the DS6800,
it may be a long long LONG time. :)


- Allen S. Rout