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. 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. > - 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. > - security 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.