Silent Hardware and Xen to KVM Migration

I replaced my main home system this week. Updating that box has always been a chore because it does a lot: it's a four-user multiseat system (downtime makes the family unhappy) as well as a server (downtime makes my clients and friends unhappy). I hadn't really intended to switch to the new box yet, but there was a weird brownout on Friday (half the house had 17 volts AC, and the other half had 110) caused by a transformer failure, and replacing that transformer took longer than my UPS batteries lasted, which meant that the system had to be booted for the first time in months, which meant that a Fedora update with new X.org 'evdev' drivers kicked in, which didn't work with the old multiseat configuration file, (big breath) ... so I had to do a bunch of troubleshooting, and figured I may as well install the new box as troubleshoot a configuration that was about to be retired.

The new machine is a Core 2 Duo E6420, 4 GB, 3x500 GB SATA-2 as a 1TB RAID-5 array, 2 Asus EN7600GT Silent PCIEx16 video cards, 2 (reused) EVGA NVIDIA MX4 4000 fanless video cards, and a DVD+-RW, all in a Sonata II case.

So there's four video cards with no fans, one CPU fan, a 12 cm low-RPM case fan, a push-pull pair of power supply fans, all in an extra-rigid steel case. It's gorgeously silent compared to its predecessor. It also has enough horsepower to run AIGLX and Compiz on all four seats plus a virtual machine for the public-facing servers (including the one running this blog).

It hasn't been trivial to set up, though. Fedora 7 went on perfectly, but I need the closed-source NVIDIA driver because nv and nouveau don't work with multiseat or AIGLX (yet -- nouveau developers, I'm counting on you!) . However, the NVIDIA driver doesn't work with Xen. The paravirtualized FC6 virtual machine from the old server (32-bit FC6) wouldn't run under the new hypervisor anyways, so I knew I was in trouble. I stewed about this overnight and decided to try migrating to a fully-virtualized KVM environment in place of Xen.

This was actually fairly painless:

1. On the original FC6 VM, running on the old box, I installed a regular kernel in addition to the Xen kernel (yum install kernel).
2. I copied the VM disk image over to the new system and ran it under KVM using the virt-manager (I had to create a new, dummy VM, then swap the copied image file for the dummy one; I also had to create a bridge network configuration -- brctl addbr br0 ; ifconfig eth0 0.0.0.0 ; ifconfig br0 ipaddress).
3. Booted into runlevel 's' and fixed up /grub/boot/grub.conf (to select the non-Xen kernel), /etc/inittab (to disable login on the serial console and enable it on VT1), and /etc/sysconfig/network-scripts/ifcfg-eth0 (to swap the new mac address for the old one).

It took me a while to figure out those steps, but they enabled me to successfully boot the old VM on the new box.

The result: a virtually silent system with great performance, some nice eye candy, and running a stock kernel.