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.)