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.)