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Re: [Xen-users] Massive iowait with Xen 3.2

To: Antoine Benkemoun <antoine.benkemoun@xxxxxxxxx>
Subject: Re: [Xen-users] Massive iowait with Xen 3.2
From: "Fajar A. Nugraha" <fajar@xxxxxxxxx>
Date: Tue, 28 Apr 2009 15:54:28 +0700
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On Tue, Apr 28, 2009 at 2:39 PM, Antoine Benkemoun
<antoine.benkemoun@xxxxxxxxx> wrote:
> Hello,
> I have gotten my new Xen server working almost perfectly, yes... almost. The
> server in question is based on Debian Lenny and Xen has been installed from
> the Debian repos. It works perfectly fine with about 8 domains (it's getting
> a little cramped on 2GB of RAM but works fine).

My RHEL 5.3 domU, functioning as firewall only, uses about 200MB of
RAM, and it won't boot if I give it less than 250MB RAM (roughly). I'm
wondering how you can cramp all those domUs.

> The last problem is that when a domain starts to generate some I/O, there is
> massive iowait.

Could it be that all domUs are swapping due to high memory use?
what does /proc/meminfo from domU and dom0 looks like? What does "xm
top" output on dom0 looks like?

Another possibility is that I/O on your system sucks (which might
happen for HVM domU). What kind of domUs are you using, PV or HVM?



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