Re: [Xen-users] How many Windows2003 on VT or pacifica

[Antoine Nivard <anivard@xxxxxxx>]

Mats,

Thanks for your reply.

I am agry for your analyse. But with my question, I would like to know if we 
can have more than 1 Windows on Xen.

If 4/5 VM per CPU is possible, with Windows as VM, for me it's ok

Thanks,

        Antoine N.




Petersson, Mats a écrit :
> > -----Original Message-----
> > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> > [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> > Antoine Nivard
> > Sent: 08 August 2006 07:26
> > To: xen-users@xxxxxxxxxxxxxxxxxxx
> > Subject: [Xen-users] How many Windows2003 on VT or pacifica
> >
> > Dear all,
> >
> > I would like to know how many Windows2003 I can run on 2 dual 
> > core 3Ghz 
> > with more than 16 Go RAM.
> > - theory?
> > - real life(experience)?
> >     
> In short: How long is a piece of string?
>
> That are idle, or that are doing something useful?
>
> What application(s) are you planning to run?
>
> How much memory does each instance of Win2K3 need?
>
> How much Disk, Network and CPU utilization does it use?
>
> There's no limit to the number of HVM guests (well, there is, but it's
> like 100 or more in 32 bit - if you run 64-bit it's ALMOST unlimited,
> but may require passing extra arguments to Xen at boot), the real limit
> will be how much CPU processing is needed to emulate the devices used by
> the guests, plus the amount of CPU needed to support the guest properly
> (with the credit scheduler this will be more stable than with the older
> schedulers!) and how much memory you give each guest. And that in turn
> will be determined by what you're doing within the guest. It's perfectly
> possible to make a dual processor machine without virtualization buckle
> at the knees from strain if you give it the right load(s), so, as
> virtualization adds load to the processor, you can obviously expect that
> the machine can start to cause trouble even with one instance of Win2K3
> under the "right" (or wrong) circumstances. [Those circumstances are of
> course when the system isn't correctly configured for the number of
> users or the type of load it's been given - not enough memory or number
> of CPU's for example]
>
> On the other hand, most Windows servers are running 15-30% of the CPU
> capacity, and nowhere near any of the other hardware limits, so you
> could probably run 2-5 of these in a single server. But there will be
> some (sometimes significant) overhead in the virtualization situation -
> particularly if there is high levels of hardware emulation involved (in
> the current implementation for Windows, ALL hardware is emulated -
> network, hard-disk, timers, graphics, keyboard, mouse, etc, etc). So a
> very disk-intensive application would have significantly increased CPU
> usage over the non-virtual version. Work is in progress to improve this,
> but it's quite clear that for the foreseeable future (several years),
> there will be some overhead in virtualizing the hardware, even if some
> extra hardware features are being added to help the processor deal with
> the virtualization of other hardware components. In the future, it
> should be possible to give each guest it's own hard-disk controller, and
> then the overhead would for disk-accesses would be eliminated - but any
> hardware that is shared must be "shared safely", which means that
> software needs to be involved in keeping track of what's going on in one
> way or another - how and where can make a small difference, but it's
> still overhead compared to the "non-virtual solution". 
>
> --
> Mats
>   
> > My hardware is VT enable
> >
> > Thanks,
> >         Antoine N.
> >
> > _______________________________________________
> > Xen-users mailing list
> > Xen-users@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-users
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