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Re: [Xen-users] mail server on a xen guest?

To: Peter Peltonen <peter.peltonen@xxxxxxxxx>
Subject: Re: [Xen-users] mail server on a xen guest?
From: Tim Post <echo@xxxxxxxxxxxx>
Date: Sun, 06 Jul 2008 01:08:49 +0800
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On Sat, 2008-07-05 at 19:25 +0300, Peter Peltonen wrote:
> I'm building a new qmail based mail server. I now have a quad-core
> server with 8 gigabytes of RAM and RAID-5 disk setup. I need to run a
> virtual web server on that host too, so I'm installing Xen on that
> host.  What I am wondering now is should I install qmail also on a
> virtual server (domU) or on the master server (dom0)? Has anyone
> experience about running qmail under xen domU? I could dedicate 1-2
> cores for the qmailtoaster domU and lots of RAM, but I'm a bit worried
> about disk I/O, as I've read that this can be a bottleneck in Xen. I'd
> like to hear stories like "I've run mail server on a domU with 100
> active domains and 10 000 incoming messages a day without problems)"
> :)

Try when possible to never, ever run a service on dom-0 that needs to
allocate memory based on what the world feeds or demands of it (i.e.
qmail, apache, etc). SSH is bad enough given the popularity of random
forky brute force attacks.

To put you at ease :

I run approximately 20 such dom-u's , with 300 virtual hosts each using
Exim, no issues.


Monkey + Typewriter = Echoreply ( http://echoreply.us )

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