I have a machine running 10.04 and am using BTRFS with lzo compression. I upgraded the kernel to 2.6.38 to enable this (using a PPA). I have my /home folder on a separate (4 TB) BTRFS drive. / is on ext4. My only complaint with this setup is that it uses the old BTRFS tools.
How can I upgrade first to 10.10, then 11.04 as required, when 10.10 uses 2.6.35? I don't want it to crash/choke on mounting /home. Will it just let me keep booting the newer kernel I have while upgrading?
LZO compressed BTRFS volumes are not supported in 10.10. Therefore we cannot upgrade 10.04 to 11.04 with a modified kernel via the upgrade path from 10.10.
In your case I would backup /home before I proceed to avoid data loss.
We are able to perform a fresh install of 11.04 with the option to keep you /home directory untouched - that is the path I would recommend here.
The installer does give you an option to "Upgrade from 10.04 to 11.04" but this is in no way the upgrade you expect as it is unable to restore sources, user accounts and applications. You will have to backup these manually and reinstall later. All user settings from /home are preserved however.
Upgrade the system and continue to boot using your custom kernel. After upgrading to 10.10, when the grub boot menu comes up, simply choose to boot with the 2.6.38 kernel. Then upgrade to 11.04. You might also just want to do a clean install of 11.04 instead of the double upgrade. This will be much faster and less likely to have problems. The 11.04 installer even now notices that you already have Ubuntu installed and offers to replace it with the new version, without formatting the disk so you keep your data files.
