Migrating to Xen

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Fedora Core 4

These steps describe how I migrated a Fedora Core 4 machine to run in a Xen slice.

I was somewhat handicapped in that I could not SSH _into_ the FC4 box for unknown reasons. I was also unable to use nfs, as it caused kernel panics. I was, however, able to ssh *from* the FC4 box.

  • First off, I created the LV target and mounted it as /mnt on the Xen dom0 as described on my Xen page.
  • Second, on the FC4 box, I determined which directories need to be created on the target: 
fc4:/# mount | cut -d' ' -f3
/
/proc
/sys
/dev/pts
/boot
/dev/shm
/tmp
/proc/sys/fs/binfmt_misc
/var/lib/nfs/rpc_pipefs
/proc/fs/nfsd
  • Then I created them: 
dom0:/mnt# mkdir -p proc sys dev/pts dev/shm tmp var/lib/nfs/rpc_pipefs

Note that I did not mkdir for the directories under /proc, since /proc is a virtual filesystem. I also did not mkdir boot, because in the virtual environment of Xen, it is not important to have /boot on a separate filesystem.

  • Then I copied the files from the FC4 machine to the target machine, by piping tar through ssh: 
fc4:/# tar -cf - usr | ssh -l root dom0 'cd /mnt; tar -xvpf -'

I repeated this for each of the directories in / that I did not already create on the target. This included bin, boot, etc, home, lib, mnt, opt, root, sbin, service, usr, var, and a few other custom directories. This could probably be combined into a single command, but I chose to break it up to monitor my progress.

  • Disable TLS 
mv /mnt/lib/tls /mnt/lib/tls.disabled
mv /mnt/usr/lib/tls /mnt/usr/lib/tls.disabled
  • Edit /mnt/etc/fstab to reflect the new virtual disk device names.
  • Copy kernel modules: 
cp -a /lib/modules/2.6.18-3-xen-686 /mnt/lib/modules
  • Unmount /mnt 
umount /mnt
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