Xen Performance

Andrew MacLachlan andrew at gdcon.net
Tue Oct 21 12:37:11 IST 2008

On Tue, October 21, 2008 11:56 am, Koopmann, Jan-Peter wrote:

> That is hard if not impossible to answer I am afraid. We are using
> MailScanner and BarricadeMX on Virtual Iron (Xen based) on several sites
> with great success. However none of them is high volume (ISP style). All
> performance comparison I have seen and the few I have done myself
> suggest (!) that a proper Xen implementation can (!) outperform ESX in
> nearly all ways but certainly not to a big extent.
> The problem is that to my knowledge VMWare simply does not allow proper
> comparison of their platform to others and will smash down all reports
> on it in public. I might be wrong though.
> I think performance in your case will not be so much depending on using
> ESX vs. a good Xen installation (with suitable drivers etc.). It is more
> a question of "can/should I virtualize this" in the first place. This
> again depends on your I/O requirements, what SAN/NAS you have available
> etc., how much RAM, what CPUs etc. If you can virtualize it with ESX I
> do not see why you would have a performance problem with Xen.
Thanks JP - I agree with your comments regarding "Should I virtualize" -
I've been working with x86 virtualization since last century (that always
sounds impressive) when the first versions of VMware Workstation were
released, and I have to keep telling people that virtualization is a great
technology, it doesn't suit every workload (put another way: Just because
you CAN doesn't mean you SHOULD). My request was more around comparing ESX
v Xen performance. I am aware of VMware viciously slapping down any
comparisons (A clause in their EULA states that you can't benchmark or
The reason I'm asking all this is because I've just released a test
version of ESVA (which was never intended to be carrier-grade) for Xen
(previously ESVA was only available for VMware platforms) so I was
interested in other peoples' experiences where they had tried MailScanner
on both platforms.


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