Slow RAID IO on PE2970

Jason Ede J.Ede at birchenallhowden.co.uk
Fri Mar 20 04:14:28 CDT 2009



> 
> We've done some more work on this box moving data off it again so we
> can look at redoing the RAID structure...
> 
> When we've a single IO stream we can easily read 20MB/s off the array
> and iostat still shows the array as not stressed at all. However, when
> its in production (its an openfiler box with ESXi hosts connecting to
> it via NFS for the virtuals) then the IO drops to what we saw earlier
> which is a few 10's or 100's of KB/s and 100% utilisation.
> 
> It all seems a bit odd... Also when copying the data off the drives
> every 5 mins or so the IO data rate suddenly drops to zero briefly. I
> think we'll run a full test on the RAID controller and the disks as the
> IO still seems poor and RAID 5 on those disks should be able to handle
> a better rate than we were seeing.
> 
> Jason
> 

Further update. We now have the box back in our office for investigation... Using the OM Live CD I've looked in Server Administrator which reports everything ok, but when I run the DELL Online Diags then on one of the drives I'm getting the following reported.

'Device reported Servo Failure'

Could this be the problem all along? A Dud drive?

Jason






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