Re: [Xen-users] Xen alternatives

[Ralph Passgang <ralph@xxxxxxxxxxxxx>]

Am Montag, 9. Januar 2006 17:57 schrieb Mark Foster:
> Pierre "Le Pierrot" wrote:
> > Hello,
> >
> > I am sending this email out because I would like to know which are the
> > free alternatives to Xen. The requirements are: Stability/Performance,
> > preferably free but it can be commercial (like VMWare and Simics), can
> > support vast amount of virtualized machines running systems Linux and
> > Windows (XP/2000/2003) for an x86 computer (like a DELL PowerEdge
> > 2850)
>
> I have worked with Xen, VMware ESX and qemu. Since you need to run
> Windows and VT technology is not widely available yet, your choices are
> reduced to full virtualization via VMware or qemu. VMware ESX is costly
> but well supported. It is actually based on Red Hat 7.x. It has good SAN
> support, training, add ons like VMTN and Virtual Center add up a pretty
> solid product that you can use for a corporate or institutional
> environment. Performance is not as good as Xen but probably on par or
> better then qemu (haven't tried the qemu-accelerator myself).
>
> qemu on the other hand is mostly open source, supports a wider variety
> of (emulated) platforms, runs on more platforms (e.g. FreeBSD and
> Windows versions are available) and also "supports" more platforms
> although it has a more limited scope of peripheral emulation (sound
> cards and such). qemu is better for labs and skunkworks-type projects,
> non-profits & startups with tiny budgets, and of course tinkerers and
> hackers.
>
> That's all the spew I have time for now, but good luck in your decision.
> HTH.

qemu is quite nice, but in my opinion more or less a tool for testing stuff, 
not for production systems with more then one virtual server running at the 
same time.

qemu can run windows without problems, but even with qemu-accelerator it's 
quite slow. On a Pentium M 1600Mhz notebook with 1GB RAM (512 dedicated to 
qemu) I hadn't much fun working with windows. I don't know if the graphical 
output makes the system slow or if it is something else (maybe even the 
complete virtualisation), but I wouldn't want to work with a virtualised 
windows on top of qemu. For me it was maybe as fast as a windows xp pc with 
about a 333-500mhz processor. You had to wait all the time until a new 
windows opens and suff like this.

For virtualizing windows hosts I would suggest using vmware or virtuozzo for 
now (and of course xen, when you are one of the lucky persons which already 
has an vt-x processor). VMWare is more or less the standard at the moment for 
complete virualisation and is working well (with a bit more overhead then 
xen). But you need to know what you want. VMWare Workstation, GSX or even 
ESX.

Virtuozzo for windows is another comercial product. It doens't virtualize a 
complete system for virtual servers, but instead it works a bit like a chroot 
(and like Linux VServers). The advantage is, then virtuozzo has just a very 
little overhead, but one of the main disadvantage is, then the security 
between the virtual servers isn't as good as with xen, vmware or somehing 
like this. If you manage to crash one virtual servers, then most likely the 
whole system will crash. It is just one Operating System for all virtual 
servers.

If you can't wait until you can buy vt-x processors I would use vmware.

--Ralph

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