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, Rafał 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. In short, Xen paravirt was very fragile and troublesome. I never
> tested Xen with hardware virtualization.
This particular problem was fixed some time ago, it hasn't happened
to my (many) dom0s in more than a year.
The RHEL5 Xen dom0 was garbage until 5.3 or so. To the point where I'd
compile my own and deal with the pain of using a non-rhel kernel with
a rehl userland.
Stability has improved vastly.
> > - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or
> > without pv drivers))
>
> PV drivers will make some difference, but the biggest performance
> difference you'll see is probably the difference between file-backed VMs
> and LVM-backed VMs. File-backed VMs are extremely slow. Whichever
> system you choose, use LVMs as the backing for your guests.
My experience has been that using qemu for disk has something of a
multiplier effect; e.g. it makes slow spinning disk noticably
slower. The paravirtualized drivers help immensely in that regard.
(how are the paravirt drivers in KVM these days? I have a server
full of kvm guests running some ancient version of ubuntu I will be
moving to RHEL6 shortly.)
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