On Tue, Nov 10, 2009 at 05:12:50PM +0200, Pasi Kärkkäinen wrote: > On Tue, Nov 10, 2009 at 03:49:59PM +0100, Dennis J. wrote: > > On 11/10/2009 03:35 PM, Grant McWilliams wrote: > > > > > > Both Novell and Oracle having been deeply involved in Xen lately, both > > > are developing and supporting their own products based on Xen. > > > > > > -- Pasi > > > > > > ___ > > > > > > > > > > > > I have no problem with a "better" solution than Xen because to be honest > > > it's a pain sometimes but at this point virtually all enterprise VM > > > deployments are either based on VMware ESX or Xen (Xenserver, > > > VirtualIron, Amazon AWS, Oracle, Sun SVM, Redhat and Suse). This tide > > > will change as KVM becomes more dominant in the VM space but I don't see > > > that happening for a while. I'm also a bit skeptical as to how well a > > > fully virtualized system (KVM) will run in comparison to a fully > > > paravirtualized system (Xen PV). I have a system with 41 VMs on it and > > > I'll be having 2 weeks of planned downtime in the near future. I'd like > > > to see how these systems run under KVM. > > > > I've been wondering about the definition of PV in the context of KVM/Xen. > > In the Linux on Linux case for Xen PV practically means that in the HVM > > case I have to access block devices using /dev/hda while in the PV case I > > can use the faster /dev/xvda. When using KVM which apparently only supports > > HVM I can still install a guest using the virtio drivers which seem to do > > the same as the paravirtualized devices on Xen. > > > > So what is the KVM+virtio case if not paravirtualization? > > > > KVM+virtio means you're using paravirtualized disk/net drivers on a > fully virtualized guest.. where Qemu emulates full PC hardware with BIOS > and all. So only the disk/net virtio drivers bypass Qemu emulation. > (Those are the most important and most used devices.) > > Xen paravirtualized guests run natively on Xen, there's no need for > emulation since the guest kernels are aware that they're being > virtualized.. There's no Qemu emulating PC hardware with BIOS for PV guests. > Oh, and Xen also has PV-on-HVM drivers for HVM fully virtualized guests to bypass Qemu :) -- Pasi