Re: [Xen-users] Better a Debian Xen PV or a Debian Hyper-V VM?

["Fajar A. Nugraha" <fajar@xxxxxxxxx>]

On Thu, Feb 12, 2009 at 9:49 PM, Heli <helicoterus-elih@xxxxxxxx> wrote:
> I installed two Debian web server which run a phpbb3 forum. One stays on
> a Xen paravirtualized domU (512 MB of ram, 1 vcpu, disc on a raw file
> file:/home/vale/debian.img,hda,w) on OpenSuse 11.0 and one run on a
> hyper-v virtual machine (512 MB 1 cpu) build on Windows Server 2008 R2.
> The performances on PV are very poor than hyper-v.
> ab -n 3000 -k -c50 http://site.lan/phpBB3/
> returns 13,22 req/sec on PV domU and 38,37 req/sec on hyper-v.
>
> Why?

I'm assuming that phpBB3 is relatively I/O intensive (since it uses
db, which I assume you also installed on the same host). In that case,
your bad numbers are probably because of this

disk=['file:/home/vale/pv.img,hda,w']

On Xen, file:/ is not recommended, and you should use tap:aio:/
instead for file-backed storage. Then again, another user reported
that even tap:aio isn't good enough
http://lists.xensource.com/archives/html/xen-users/2009-01/msg00820.html

So in short, if you use Xen PV, you might want to consider using
LVM/partition-backed storage.

Regards,

Fajar

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