There are not any performance improvements when the TSM Recovery Log or
TSM Data Base is put on RAW volumes. It would be much easier to manage
if the environment is all JFS. There may also be a need in the future to
run multiple instances of the TSM server code on the same box. Which RAW
could cause problems.

Also there are some concerns when working with RAW volumes. 

        Do not use AIX to mirror Raw Logical Volume with TSM. Instead
use TSM mirroring facilities. AIX puts information in a control block on
disk which will overwrite TSM's control information. 
        Do not change the size of RLV's using SMIT. Please refer to 'TSM
for AIX Administrators manual for EXTend DB and EXTend LOG commands. 
        The TSM Administrator must be careful not to start multiple
instances of TSM Server code which may use the same RLV's. With AIX
there is no locking when using RLV. TSM attempts to fix this by
implementing locks using files in the /tmp directory. These locks may be
deleted if programs are run which clean up the files in the /tmp
directory. 


Jim Hunt
_______
GlassHouse Technologies, Inc.
jhunt AT glasshouse DOT com
 
-----Original Message-----
From: Paul Zarnowski [mailto:psz1 AT CORNELL DOT EDU] 
Sent: Thursday, January 22, 2004 1:36 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: RAW vs. JFS question

At 06:24 PM 1/22/2004 +0100, you wrote:
>On Thursday 22 January 2004 15:38, Bill Boyer wrote:
> > The "new" TSM runing guide recommends using RAW volumes for
performance
> > reasons.

I think IBM's recommendation is raw for DB and LOG, and JFS for stgpool
volumes (because of potential readahead benefits in JFS).

>And what about the DirectIO and AsyncIO?  If you use DirectIO, don't
you
>bypass the file system cache?

DirectIO is only usable on AIX for LVs under 2G.  That's pretty
restrictive.

>Stef

..Paul



--
Paul Zarnowski                         Ph: 607-255-4757
719 Rhodes Hall, Cornell University    Fx: 607-255-8521
Ithaca, NY 14853-3801                  Em: psz1 AT cornell DOT edu