xen virtualization and linux distros

[CLIFFORD ILKAY]

On Saturday 10 February 2007 03:57, Christopher Friedt wrote:
> Hi everyone,
>
> My company would like to set up some virtualization on one of our
> multi-processor / multi-core server machines, using Xen.
>
> I've heard excellent things about Xen. The question is, which
> 'distro' should one use with it.
>
> I've been a gentooer for quite a while now, and believe that it's
> pretty great, even for server administration. The Xen / Gentoo
> documentation is pretty good, and they've apparently even done it
> somehow so that when you make a new image, it doesn't have to be a
> whole distro - only some basic necessities.
>
>
> This is sort of a survey, but does anyone have experience using Xen
> for virtualization?
>
> If so, which flavour of linux was used?

I integrated Xen 2x with Mandriva in June, 2005 and have been happily 
using it ever since. Getting Xen to run on any distro isn't that 
hard. The real work was in integrating it with the networking and 
firewalling scripts, Shorewall in Mandriva's case, Mandriva's msec 
system, dealing with issues related to not having access to the bare 
metal from the virtual machines, and so on. At the time, the only 
distros that integrated Xen were Suse and Fedora Core and "minimal" 
installations of either weighed in at a porky 800 MB. My Mandriva 
dom0 is 210 MB and runs fine with only 64 MB of RAM allocated to it. 
I could get that even smaller if I did away with urpmi, which I 
won't.

On top of that dom0, I run Mandriva Gentoo, CentOS, and Debian Etch, 
Ubuntu. You can run whatever distro you like in a domU (virtual 
machine).

> Are there any dis / advantages that can be highlighted?

I spent a fair amount of time on the Xen IRC channel and have found 
the people there extremely knowledgeable and helpful. I have no 
complaints with Xen.

OpenVZ is another option I had looked at last year. It seemed like I 
could put more virtual machines on a given box (without overloading 
it) due to the way that OpenVZ allocates resources compared to Xen 
but I have never put anything into production. Xen has better 
isolation between virtual machines but in most hosting scenarios, 
that difference is negligible.

When I tried OpenVZ, it was with a Fedora Core 5 kernel. I submitted a 
bug report when I got stack dumps on boot even before modules were 
loaded. This led to an interesting conversation on IRC with one of 
the lead developers who said that in production, they prefer 
RHEL/CentOS because its product lifetime is 5-7 years. He said that 
Red Hat backports security fixes to their stable kernel so it is 
mature and contains only required fixes. He said that distros like 
Fedora and OpenSuse often include kernels that are not ready for 
production so new bugs are introduced constantly. He had no opinion 
on Debian because he didn't use it. Take that conversation with a 
grain of salt because it was on May 30, 2006 so things could have 
changed since then, though I don't think the Fedora or OpenSuse 
situation is any different today or ever will be given that both are 
bleeding edge distros.
-- 
Regards,

Clifford Ilkay
Dinamis Corporation
3266 Yonge Street, Suite 1419
Toronto, ON
Canada  M4N 3P6

+1 416-410-3326
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