Upgrading your Debian VPS from lenny to squeeze

Below are my notes recorded when migrating from Debian 5.0 (lenny) to 6.0 (squeeze) on my BitFolk VPS; hopefully others will expand upon it with their own notes.

Background Work

• Recommended: Move to UUIDs in /etc/fstab and /boot/grub/menu.list (kernel and kopt lines) if that isn't already the case.
• Remove clocksource=jiffies from your kopt line if you have it in /boot/grub/menu.list.
• Is your root partition on /dev/xvda1 (as opposed to /dev/xvda)? If so, make sure that fdisk -l /dev/xvda works. If it doesn't you need to have your /dev/xvda1 device renamed to /dev/xvda. Contact support if that's the case.
• Check if you have xen.independent_wallclock in /etc/sysctl.conf; remove it if you do.

Perform the upgrade

• If you use Debian Volatile, disable it and use the following instead:

deb http://apt-cacher.lon.bitfolk.com/debian/ftp.uk.debian.org/debian/ squeeze-updates main non-free

• Follow the upgrade instructions at http://www.debian.org/releases/squeeze/i386/release-notes/ch-upgrading.en.html

Before rebooting

• Make sure you have grub-legacy installed.
• Run update-grub to see which kernels it finds.
• Make sure that your /boot/grub/menu.lst is actually going to boot into the right kernel.

Alternatives to upgrading in-place

If you can't afford the down time then you might like to take advantage of BitFolk's free offer of a new VPS to migrate to over a period of two weeks.

You can also completely reinstall your VPS yourself to a range of distributions. Upgrading Debian distributions in-place usually works well, however.