Agreed ... that happened to us.  What RAID5 *did* do for us was to increase the
system's stability -- we never experienced an outage due to a hard failure of a
RAID5 HDA.  Also, at the time we decided to go with it, we needed to reduce the
overall equipment footprint on the floor, and this was the most compact
technology (GB/sq. ft) available for MPE/iX in 1993, IIRC.
----
Lee Gunter                    The Regence Group
Supervisor, TRG HP/MPE Systems     503.375.4498
----
Opinions expressed are solely mine.




From: Bill Lancaster <[log in to unmask]> on 12/07/99 06:55 PM

Please respond to Bill Lancaster <[log in to unmask]>


To:   [log in to unmask]
cc:    (bcc: Lee Gunter/BCBSO/TBG)
Subject:  Re: [HP3000-L] RAID5 Disc's




I have to disagree.  I've never seen RAID 5 increase anyone's HP 3000
system performance.  In *many* cases I've seen RAID 5 seriously hurt
performance.  In many of those cases, going back to RAID 1 or JBOD in turn
increased performance.

Bill

At 04:29 PM 12/7/99 -0800, Steve Dirickson wrote:
> > over RAID level in these arrays.  If you use RAID 5 you'll
> > pay a price in performance.
>
>Probably not. RAID5 has slightly worse write performance than a single
>spindle (due to the need to update the parity information), but
>substantially better read performance. Since reads outnumber writes by an
>order of magnitude or two (or three...) in "normal" installations, RAID5
>should *increase* system performance.
>
>Simple explanations/discussions:
>  http://www.digidata.com/raiddesc.html
>  http://www.acc-sd.com/site/raidlevels.htm
>  http://www.adaptec.com/technology/whitepapers/raid.html (note the comment
>that "Database servers are an example" of where RAID5 works well)
>
>More extensive discussions:
>  http://www.eurologic.com/tn/tnwp2.htm
>  http://www.acnc.com/raid.html
>
>
>Steve Dirickson   WestWin Consulting
>[log in to unmask]   (360) 598-6111