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

[John Haxby <john.haxby@xxxxxxxxxx>]

Nico Kadel-Garcia wrote:
> Peter Peltonen wrote:
> > I'm building a new qmail based mail server. I now have a quad-core
> >   
> *WHY*??? Qmail has many cool technical features, but it's licensing 
> has been extremely burdensome, as has its packaging. Mr. Bernstein has 
> relented and placed his work in the public domain, but it languished 
> for years for that reason. Debugging it in any environment without 
> your own sophisticated sys-geek to work around Mr. Bernstein's 
> policies is.... awkward.
I agree completely with this -- qmail is a pain and there are good 
reasons why it's not in the major distros.
> > 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)"
> > :)
> >   
> Why not use Dovecot? It's built into contemporary Fedora and CentOS, 
> which themselves are well integrated with Xen and perform reasonably 
> well in paravirtualization.
> And you can use MRTG and tools like it to monitor your disk I/O now, 
> to get some sort of standard to compare against.
RAID5 isn't going to be good for mail: a lot of the disk-writes are 
going to be very small and there are going to be a hell of a lot of 
them, especially with that kind of incoming load.   Actually, with that 
kind of incoming load I don't think you're going to want to run the mail 
server on anything other than the bare metal anyway: virtual machines 
work well when you have servers that are individually relatively lightly 
loaded and it doesn't look as though yours is.
jch

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users