[CentOS] XEN or KVM - performance/stability/security?
Pasi Kärkkäinen
pasik at iki.fi
Tue Jun 5 06:36:36 UTC 2012
On Fri, May 11, 2012 at 03:46:43PM -0700, Gordon Messmer wrote:
> A late reply, but hopefully a useful set of feedback for the archives:
>
> On 04/20/2012 05:59 AM, Rafa?? Radecki wrote:
> > Key factors from my opint of view are:
> > - stability (which one runs more smoothly on CentOS?)
>
> I found that xenconsoled could frequently crash in Xen dom0, and that
> guests would be unable to reboot until it was fixed. I also found that
> paravirt CentOS domUs would not boot if they were updated before the
> dom0.
>
This was a problem in RHEL5/CentOS5 Xen. It was fixed in upstream Xen years ago.
I think it was fixed finally in RHEL5/CentOS5 Xen in 5.7 or 5.8.
The workaround was to simply kill+restart xenconsoled. No reboot required.
Also I think the xenconsoled bug only happened on 32bit hosts.
> In short, Xen paravirt was very fragile and troublesome. I never
> tested Xen with hardware virtualization.
>
Xen PV has been rock solid for me :)
> I have had no such problems with KVM. In my experience KVM is much more
> stable than Xen paravirtualization. Xen HVM probably would suffer at
> least some of the same problems.
>
You should compare Xen HVM with KVM, and you said you haven't been running Xen HVM.
>
> There have been bugs that allow guests to escalate privileges and access
> host resources, but they're relatively few. I don't think there's a
> significant difference between the two in this area.
>
> Overall I advise the use of KVM. It should be more stable, and has the
> advantage of Red Hat support.
>
Xen is supported by Red Hat support in RHEL5.
-- Pasi
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