[Xen-users] Slow domU disk performance

To:	Xen <Xen-users@xxxxxxxxxxxxxxxxxxx>
Subject:	[Xen-users] Slow domU disk performance
From:	"Eric Peterson" <srcfoo@xxxxxxxxx>
Date:	Thu, 29 Jun 2006 12:25:24 -0500
Delivery-date:	Thu, 29 Jun 2006 10:26:08 -0700
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Hi,

I am running Xen 3.0.2 on dual core Opteron with 6GB RAM.  The machine
works fine except my guest domains have a problem when disk I/O is
involved where they become unresponsive and top shows "100% wa" for
cpu usage. This happens when running a larger select from a postgresql
database.  dom0 and my other domU's remain responsive the whole time
so it seems like it is an issue with the configuration of the domU and
not with the hardware or underlying system.

I'm exporting the disks as SCSI devices and the the main disk is a
SATA RAID array running of a 3ware card. I know with ATA/IDE disks you
can use hdparm to tune the disk, but since these SATA drives are seen
as SCSI drives that's not possible AFAIK.

Does anyone have any recommendations or places to start looking? I
searched the list, but couldn't find a whole lot.

Thanks,
Eric

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