aacraid and extremeley high iowait

[Stephen John Smoogen]

On 6/15/06, Kris Doosje <k.doosje at nido.nl> wrote:
> I have the same problem on a PowerEdge 1800. I'm running Red Hat Enterprise AS 3 on the machine. In the machine are 6 SATA disks (80GB). Two raid arrays are configured: 2 disks in a RAID1, and 4 disks in a RAID1+0. When I read or write a large amount of data, IOwait reaches values around 100% and the system becomes very, very slow.
>
> Because of this, the machine is almost not used at the moment, which is a shame because it should be a very powerfull machine! Hopefully there's a solution to this problem..
>

I have talked to techs who have seen these issues with aacraid
controllers. Some got acceptable performance with a BIOS updates to
the system. The others just went with other hardware controllers and
swore never to touch an aac again. The problems seemed to not be with
the driver but with the controller itself under certain loads (they
could simulate the same large waits with windows).


-- 
Stephen J Smoogen.
CSIRT/Linux System Administrator