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Re: [Xen-users] Re: Performance Issues: I/O Wait

To: Nick Couchman <Nick.Couchman@xxxxxxxxx>
Subject: Re: [Xen-users] Re: Performance Issues: I/O Wait
From: Stephan Seitz <s.seitz@xxxxxxxxxxxx>
Date: Wed, 24 Oct 2007 15:17:07 +0200
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Nick Couchman schrieb:
> Stephan,
> Thanks for the tips - I'll give them a try.  One clarification - for
> disabling transmission checksums, is that inside the domU or inside
> dom0?

Hi Nick,

I dont' know if it's really necessary, but we're disabling transmission
checksums on every domain including dom0.
Btw. some weeks ago i noticed a thread at the list with problems using
tg3 cards. As we don't own cards with Broadcom Tigon3, i didn't mention.

> Some of the tests was using NFS, but lately I've been testing with iSCSI
> and even local block devices and it seems to happen on those, too,
> though not to the same degree.

This sounds really strange. We've tried different kinds of domU disks and
are currently using dom0 LVM's on locally attached raid arrays. It is
really paranoid, but we avoided disk images with the same filesystem as
the underlaying. so we didn't test ext3 on ext3 or xfs on xfs. Besides
this restriction, we didn't notice any BIG performance problems.



Stephan Seitz
Senior System Administrator

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