Upgrading from Debian Lenny (5.0) to Debian Squeeze (6.0) under Xen

Debian Squeeze was released 06.02.2011 and Lenny’s support will (probably) be is discontinued since 06.02.2012.

Problem: apt-get update && apt-get dist-upgrade broke everything, server did not boot anymore.

Troubleshooting: squeeze has grub2, which our Xen 3.x and pygrub didn’t understand

Solution: upgrading with following steps, use apt-get or aptitude, whichever you like.

1. Update Lenny

   aptitude update
   aptidude upgrade

2. Replace lenny with squeeze in /etc/apt/sources.list – or add necessary entries to another file under /etc/apt/sources.list.d/

   deb http://ftp.fi.debian.org/debian/ squeeze main contrib non-free
   deb http://ftp.fi.debian.org/debian/ squeeze-updates main contrib non-free
   deb http://security.debian.org/ squeeze/updates main contrib non-free

3. Update repository

   aptitude update

4. Upgrade critical parts first

   aptitude install dpkg apt aptitude

5. (Dist-)upgrade rest

   aptitude upgrade
   aptitude dist-upgrade

6. Replace grub2 with grub1 (or just keep your old menu.lst at /boot/grub/)

   aptitude purge grub-pc
   aptitude install grub-legacy

7. Check that /boot/grub/menu.lst exists and defaults to right kernel
8. Reboot and hope for the best

Also remember to use 2.6.39 -kernel from backports for live migration to work.
Update 01/2013: 2.6.32 -kernel usually works just fine, Lenny’s EOL date is 6.2.2012.