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

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Antoine Nivard
> Sent: 09 August 2006 12:33
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] How many Windows2003 on VT or pacifica
> 
> 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.

You can definitely run more than one Windows instance on one machine with Xen, 
no worries there... But the performance and well-behaving of the system will to 
a large extent depend on what you're actually doing within that Windows guest - 
is it just sitting there answering the odd Web-request, or is it a very busy 
file-/mail-server for a big office?

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

It's POSSIBLE, but I wouldn't recommend it if you've got more than a little bit 
of load on any of the machines... 

--
Mats
> 
> 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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