PERC6 RAID5 under high i/o load (iops, not b/w), extreme latency

[cupertino]

I did not follow all of that thread. So if my information is redundant
just ignore. 

We had performance issues and tried everything you can think of. Then
Dell support gave us the hint to full initialize the RAID in CTRL+R BIOS
(no fast init and let the init complete while in controller BIOS). After
that procedure all our problems miraculous disappeared. 

Bye.


On Thu, 2011-04-07 at 11:44 -0600, Stephen Dowdy wrote:
> I realized, i didn't reply-all back to the list:
> 
> > Blake,
> >
> >> Sudden changes in PERC performance usually link back to BBU changes.
> >> Check the current cache policy against the configured/default cache
> >> policy to ensure that the array is really in write-back mode:
> >> megacli -LDInfo -LAll -aAll
> >
> > I'd already looked at this.  the BBU Learn period is 90days (default, i
> > think), and this is an ongoing constant problem.
> >
> >> I've seen the PERC5/6 do 1000-2000 IOPs with the right workload in
> >> write-back mode, so I know they're capable of it.
> >
> > thanks for that feedback.
> >
> > thanks again,
> > --stephen
> >
> 
> 
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