RE: RAID system max throughput

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Fri, 07 Dec 2001 11:45:28 -0800
Message-ID: <F001.003D7D0D.20011207112521@fatcity.com>

tday6 - Thanks for replying. No, the RAID seems to perform fine. I can perform certain Oracle operations (usually DBA activities) and kick the RAID I/O really high (considerably below the vendor specs). In normal usage the I/O is far below this level.

Statspack analysis shows disk waits to be our greatest wait. Does this mean that I have a superbly tuned system and there is nothing more to do? If I can get an amen to that then I can leave happy for the weekend. Part of what concerned me was that none of the Oracle tuning books I have mentions vendor specs for RAID I/O at all.

Thanks for your ideas.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----

Sent: Friday, December 07, 2001 12:13 PM To: Multiple recipients of list ORACLE-L

I'm not sure that I understand the question. Is it:

Under max load the RAID does not perform up to its specs?

B. Oracle does not stress the RAID enough for it to reach its max performance.

If A, then have the RAID vendor fix whatever the problem is.

If B, then good for you. You have a well designed system.

                    DENNIS

                    WILLIAMS             To:     Multiple recipients of list
ORACLE-L      
                    <DWILLIAMS           <ORACLE-L_at_fatcity.com>

                    @LIFETOUCH.CO        cc:

                    M>                   Subject:     RAID system max
throughput           
                    Sent by: root

 

 

                    12/07/2001

                    11:40 AM

                    Please

                    respond to

                    ORACLE-L

Whenever I discuss disk waits with my system administrator, I always get the
reply that "the RAID system isn't anywhere near its rated throughput". Maybe
I'm wrong, but I don't see any of the tuning books mentioning that as a relevant performance characteristic. However, I've never been able to move the discussion beyond this point. Can anyone straighten me out on this point
or point me to a resource that might be applicable.

Our system is Oracle 8.1.6, Compaq Tru64. We use hardware RAID-5 with a battery-backed RAM cache, and have about 3 RAID sets (plus some extra disks for redo logs, etc.), and performance is fine, but I'm always looking as to how we can improve Oracle performance. The application is our corporate ERP system.

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
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