High IO Wait - PowerEdge 2650 - Perc 3/Di

Eric Rostetter rostetter at mail.utexas.edu
Fri Jan 19 11:28:55 CST 2007


Quoting Ray Van Dolson <rvandolson at esri.com>:

> Jeff, also running some 2650's.  RHEL3.

We run _lots_ of these, but _none_ with the hardware raid.  We specifically
avoided the hardware raid in these units.  We run software raid instead.
All with RHEL 3 or Centos 3  (originally they ran RHL 8 or RHL 9).

> The machines seem to have similar
> issues when placed under high IO load (DB servers).  We'll see

We have no issue under high load, at least none that tuning didn't fix.

> errors in dmesg
> or via netdump such as the following:
>
>   aacraid: Host adapter reset request. SCSI hang ?
>   aacraid: Host adapter reset request. SCSI hang ?
>   aacraid: Host adapter reset request. SCSI hang ?

Definately the raid card being flakey, IMHO.

> Several machines do this, so we're pretty sure it's an issue with the PERC or
> the driver.

Yes, indeed.  My motto is never run the Adaptec PERC controllers.

> I've seen threads in the past on IO issues with the 2650's.  Never   
> really seen
> a clean cut solution though.

Mostly they are problems with the Adaptec RAID/PERC cards, and the only
clear cut solution is not to use them...

> Ray

-- 
Eric Rostetter
The Department of Physics
The University of Texas at Austin

Go Longhorns!



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