Re: [Xen-users] Hardware configuration?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> On Thu, Apr 3, 2008 at 1:21 PM, Rudi Ahlers <Rudi@xxxxxxxxxxx> wrote:
> > How many users will connect to it? What will the concurrent connections
> > be?
>
> Not that many -- 2 or 3 users max, really.  I host a Subversion repository
> for a couple of other folks, and then my local network.  Sounds like 4
> cores would be ample.

Yes, I expect it really would be ample - especially if the VMs aren't 
concurrently active most of the time.  You could possibly get away with less, 
depending very much on what exactly you plan to do.

Your 4 core CPU (I'm assuming you're looking at Intel Core 2?) should have 
virtualisation tech, so as long as you don't get a silly motherboard that 
disables it, full virtualisation should work too (i.e. Windows, amongst other 
things).  Sounds like buying a Xeon would probably be overkill.

> I'm not certain of load -- assuming that Xen itself 
> doesn't really add much, the load should be pretty low (if not idle) except
> when MythTV is processing video

What exactly are you doing with MythTV?  Some folks have dedicated a PCI TV 
card to a VM and run Myth in that domain to record it, etc.  That's doable 
but obviously it'll be simple if you're just using Myth as a storage server 
or something - less faffing around.  Works either way though.

> and I was planning on limiting it to 2 
> CPUs, so again 4 cores should be just fine.
>

You can limit a domain to a certain percentage of CPU time and to a certain 
number of concurrent CPUs, which should help.

> I had kinda figured 256MB for the basic machines and then 512MB for a
> couple of them (MythTV and workstation),

When you say "workstation", do you mean that you'll actually be logging into 
that domain on the physical terminal?  If so, that domain will have to be 
dom0 (the master domain).  This is unfortunate, security-wise, given that 
dom0 has control over all other domains.  However, for a small home server 
(especially as you probably trust your home users!) I don't think this'll be 
a big problem - just something to be aware of.

Also, if you're using it as a workstation, you should consider your graphics 
set up.  It can be a pain to get 3D graphics drivers working under Xen, so 
you should research this first.

> so my 4x256MB + 2x512MB memory 
> sizing. But, maybe 512MB is the comfort spot for a Linux box...  Which is
> good to know -- I'd rather spend my $$ wisely.  :-)

Indeed!

Cheers,
Mark

-- 
Push Me Pull You - Distributed SCM tool (http://www.cl.cam.ac.uk/~maw48/pmpu/)

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