From: Will Kooiman,  kooiman@interserv.com
Subject: Re: HELP: Info about ORACLE7 Performance on RAID
Date: 1995/08/08
Message-ID: <406gd8$sui@data.interserv.net>#1/1
references: <3vqpac$9rp@maverick.tad.eds.com>
organization: Computer Systems Authority
newsgroups: comp.databases.oracle


>   Peter Constantinou <rosepete@xs4all.nl> writes:
>  X-URL: news:comp.periphs.scsi
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>  
>  Does any one have experience of ORACLE7 applications running on RAID disk
>  arrays. I have been told that performance is poor for Oracle V6 applications,
>  but cannot find anyone with experience of ORACLE7.
>  
>  FYI The application is ORACLE7 v7.0 running on IBM RS/6000 under AIX 3.2.5
>  (soon to be ORACLE7 v7.1 under AIX v4.0). We are looking to purchase 12Gb of
>  Seagate or IBM based RAID (configured for RAID level 5).
>  
>  Thanks in advance for any info
>  
>  Peter C
>  
>  -- 
>  rosepete@xs4all.nl     Phone: +31 10 4987 727     Fax: +31 10 2120 295
>  EDS BV, Electronic Data Systems, The Netherlands.
>  
>  
>>>>

I've used RAID 0,1,0+1, and 5 with Oracle 6 and 7, and saw no difference in 
performance between the two.

I didn't see a lot of improvement in TP oriented access, but I saw a big 
improvement in decision support queries  (table scans).

I'm not a big fan of RAID 5 due to it's VERY poor write performance.  If you think it's
bad when all the disk drives are working, wait until a drive fails.  You still have your
array, but the system seems to halt due to poor performance.

My absolute favorite is RAID 0+1.  This gives you redundancy, with unbelievable
performance.  But, it costs a lot since you must buy twice as many disk drives as
you would have to otherwise.

Quick RAID overview:

Without going into a lot of detail, here's the scoop on the most popular RAID levels.

RAID 0 (mirroring)	reads are slightly faster,  writes are slightly slower  (with redundancy)
RAID 1 (striping)	reads are much faster, writes are much faster  (no redundancy)
RAID 0+1		reads are much faster, writes are much faster,  (with redundancy)
RAID 5		reads are much faster, writes are much slower (with redundancy)


Hope this helps,
Will Kooiman