Amen! 


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
John Monahan
Sent: Tuesday, June 20, 2006 1:35 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] TSM diskpool on SATA

> Did you do any FILE devclass work?  It sounds as though your miserable

> performance was head thrashing, which we'd get in multiple LV DISK 
> devclasses, and also in FILE devclasses.  Darn. :)

No I was using a DISK devclass, but I'm almost positive it wouldn't have
made any difference with FILE devclasses.  Some of the LUNs were faster
than others (first ones in the RAID group created) and as soon as I was
writing to more than one at a time my performance would tank even
further, which shouldn't be any different had I used FILE devclasses.  I
would have tried file devclasses with more time for performance reasons,
but I had spent too much time on it already and the 150 MB/sec writes
for my diskpool was adequate for my needs and outpaced the capabilities
of my single Gigabit network connection to the TSM server, so I moved
on.

Hundreds of LVs with FILE devclasses on fibre disks would probably do
exactly what you are looking for and provide excellent performance.
SATA just isn't good enough at multiple, simultaneous I/Os to the same
set of disks yet.