I agree with Tim (and Andy earlier).  We use 7137-514 RAID for DB (now
almost 50GB and spread over 2 RAID arrays).  We are shortly to install
SSA RAID with fast write-cache and will be looking to move the DB to
that, if it proves faster ...  we'll report findings on that score.

When the DB was smaller we experimented with SSA mirroring and it wasn't
clear cut in all operations.  On balance we found 7137-514 RAID faster
and we believe that the biggest factor there was the write-cache on the
RAID array.  The SSA had no write cache available.

During experiments we have had mirrored 7137-514 RAID for DB and noticed no
discernable loss in performance by adding mirrors (ADSM again).

We also use SSA for recovery log and have ADSM mirrored copies.

The only thing we use AIX mirroring for is at logical volume level for
storage pools :  there is no ADSM option to mirror stg pools.  We would
not use AIX mirroring for DB or LOG for all the reasons said before.

Regards, Sheelagh

------------------------------------------------------------------------------
Sheelagh Treweek                         Email: sheelagh.treweek AT oucs.ox.ac 
DOT uk
Sheelagh Treweek                         Email: sheelagh.treweek AT oucs.ox.ac 
DOT uk
Oxford University Computing Services     Tel:   +44 (0)1865 273205
13 Banbury Road, Oxford, OX2 6NN, UK     Fax:   +44 (0)1865 273275
------------------------------------------------------------------------------
> From owner-adsm-l AT VM.MARIST DOT EDU  Mon Jan  5 17:03:05 1998
> From owner-adsm-l AT VM.MARIST DOT EDU  Mon Jan  5 17:03:05 1998
> Encoding: 42 TEXT
> Date: Mon, 5 Jan 1998 11:44:53 -0500
> From: "Pittson, Timothy ,HiServ/NA" <tpittson AT HIMAIL.HCC DOT COM>
> Subject: Re: ADSM mirroring vs. AIX mirroring
> To: ADSM-L AT VM.MARIST DOT EDU
>
> Joe,
>         If it comes down to using ADSM or AIX to mirror the database, I'd use
> ADSM mirroring.  I think the big advantage to using ADSM mirroring is in
> the event of the system crashing during a DB write and causing DB
> corruption.  With AIX mirroring, I think you're SOL but with ADSM
> mirroring, if the write didn't complete to both copies of the DB, you
> stand a chance of one copy of the database not being corrupted.
> Regarding RAID, I had posted questions to the ADSM-L listserver a couple
> of years ago about this and received some very helpful information -
> somebody had even done some benchmarking (7137 array vs. SCSI vs. SSA or
> something like that - this was a long time ago - at the time, the 7137
> outperformed the other options ).  We decided on using a dedicated
> 7137-514 disk array configured for RAID-5 w/hot spare for our ADSM DB
> (16 GB) and have been very happy with the performance.  There had also
> been some posts about using mirroring/striping with SSA disks but I
> don't know what the results of that were.  I keep the recovery logs on
> separate dedicated SSA disks and use ADSM mirroring to mirror them.
>
> Tim Pittson
>
>
> >-----Original Message-----
> >From:  Joe Morris [SMTP:morris AT UNC DOT EDU]
> >Sent:  Monday, January 05, 1998 10:49 AM
> >To:    ADSM-L AT VM.MARIST DOT EDU
> >Subject:       ADSM mirroring vs. AIX mirroring
> >
> >I've been browsing through the ADSM archives at Marist and could not find
> >what I was looking for.  Setting up a new server that has ample space to
> >replace our old ADSM server.
> >
> >What are the pros and cons of using ADSM and AIX to mirror the database
> >and log volumes.  Mainly focusing on differences between using AIX
> >mirroring and the built-in mirroring in ADSM.
> >
> >I had considered a RAID configuration, but it seems like that is not such
> >a hot solution for the database for performance reasons.  Am I wrong?
> >
> >_______________________________________________________________
> >Joe Morris  -  morris AT unc DOT edu  -  http://sunsite.unc.edu/morris
> >Academic Technology and Networks, Development and Eval Services
> >University of North Carolina at Chapel Hill      PGP by request
>