That sounds like software RAID5, where the host computer has to do the
parity calculations and the extra disk I/O in addition to its normal
workload. With a dedicated RAID controller running the array, I don't see
how a RAID5 array could have overall worse performance than a non-RAID setup
except in a very write-intensive system. Well, unless the RAID controller
was running on a Z80B or something....

> 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
>