We've been using Xen 3.0 for the past 18-ish months on a couple boxes here and were quite impressed with it, especially when using the xen-tools package on Debian. But, it couldn't run FreeBSD or Windows guests on our existing hardware, so we bought shiny new Opteron 2000-series systems with SVM support. And then the problems began.
Xen 3.1/3.2 broke too many things for us (especially in the network setup), and we could not get a stable, working, reliable dom0 let alone any domUs. Mainly due to our hardware requiring a newer Linux kernel than 2.6.18 (RAID controller and NIC weren't supported until 2.6.20). So we started testing KVM, originally with kvm-60 and kernel 2.6.22 on Debian Lenny. Since then, we've moved to kernel 2.6.24 and 2.6.25, along with kvm-69. We've been running Windows XP, FreeBSD, and Debian guests for the past few months with very few problems. Today, I managed to get a couple Linux guests to load using the virtio drivers in kernel 2.6.25. Colour me impressed! I thought the emulated e1000 interface had good performance: the network throughput of virtio_net (as tested using iperf) is wire-speed. I was able to saturate a gigabit link using iperf from a guest running with virtio_net! Average throughput was 860+ Mbps, with highs around 980 Mbps. That, combined with how easy it is to manage kvm (I wrote my own management scripts and config file format that is a lot easier to read than the Xen ones), configure networking in the host (done using the distro tools, not some arcane python scripts), and get hardware driver support in the host (standard distro kernels, not ancient xen-specific ones), makes it very hard to find reasons to run Xen. The only reason I can find, is if you have hardware that doesn't support VMX/SVM, but is supported by kernel 2.6.18, in which case Xen 3.0 works quite nicely (not 3.1 or later). Kudos to the kvm devs, the kernel devs, the qemu devs, and the rest who are involved in making KVM work so well! For those interested, I've put some iperf results into the KVM Wiki (http://kvm.qumranet.com/kvmwiki/Using_VirtIO_NIC), along with info on the management scripts/config file format I use (http://kvm.qumranet.com/kvmwiki/HowToConfigScript). Now, if only the FreeBSD port of KVM could be completed, so we could use ZFS in the host instead of LVM. ;) -- Freddie Cash [EMAIL PROTECTED] -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
