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Debian Lenny and grub with /boot in LVM

At last, I can put my /boot partition in LVM.

  • Get the Debian box up to Lenny.
  • Note that I accidentally trashed my MBR and had to boot into rescue mode while working out these steps. You shouldn’t do this if you follow all of the instructions, but you ought to have media handy.
  • aptitude install grub-pc (Note: this will remove the old grub package and offer to chain load grub2 from your existing grub. Do this. If you have problems you can still boot.)
  • Verify you can reboot.
  • Remove the old grub MBR and put in the grub2 one with upgrade-from-grub-legacy
  • Hide your /boot/grub/menu.lst so you aren’t tempted to edit it.
  • Your basic configuration, like kernel command line parameters is now in /etc/defaults/grub, there is also /etc/grub.d/* which I hope to never touch.
  • Move your /boot into the LVM. You could tar up your /boot partition, unmount it, and extract it onto the root partition. You could also make a new LVM managed /boot if you like it on its own partition. I was out of space in the volume groups, so I went with /. If you didn’t make a new /boot, remember to take /boot out of /etc/fstab.
  • dd zeros onto your old boot partition to make sure you aren’t deluding yourself.
  • Edit /etc/defaults/grub to add GRUB_PRELOAD_MODULES=lvm
  • Go back and make certain you did the previous step. I made an unbootable system before I learned that little tidbit.
  • Do an update-grub and a grub-install /dev/sda or whatever your disk is.
  • Go back and make sure you did the grub-install… Just update-grub is not enough to pick up the lvm module.
  • Reboot and rejoice.

I am left wondering what silliness lead to GRUB-2 being version 1.96, but I am happy.

You saved me many (more) hours of head pounding with this blog entry.  I am thoroughly grateful.

At some point in the past I managed to screw up my file server's lenny install in such a way that I ended up with the non-lvm ext2 boot partition commented out of fstab and a separate /boot directory on the lvm root.

I forgot about this incident and went about continuing to run apt-get dist-upgrade periodically.  Everything worked until I went to squeeze and rebooted, at which point I made some more poor choices ("Why am I not running the new kernel?  I'll just apt-get remove the old one!") and ended up unable to mount ext2 partitions (while still able to boot from one).

After about eight hours of head scratching I found this page and by following your steps had no trouble upgrading to GRUB 2 which booted the new kernel which fixed all the problems, allowing me to get on with my life (such as it is).

You are awesome and so is GRUB 2.

You should note that grub-pc for lenny is missing part_msdos.mod and will not install, you need to fetch it from backports to get the file.

Thanks for the info though, it helped me to confirm what I was doing would work before I sent a remote machine through a reboot (I know, dangeous, but couldn't be helped)
I have been trying to do this for 3 whole days and I finally found this post by accident. I have tried to do this with Arch Linux and Fedora and had no success. Even Google yielded no answers until I tried "Debian grub2 lvm /boot" and found this. Even though this is not written for squeeze I managed to take the bottom half and make this work. I even went as far as asking on 2 forums and in IRC channels for multiple OS's, even bugged some friends and got the usual "why would you want to do that?". Sir, I cannot thank you enough. Looks like I'm a Debian user now thanks to blogs like this.
Debian Squeeze, VirtualBox 4.0 from backports.

Debian 6.0.4 installer .iso

6 virtual disk devices
-> one physical raid partition per device
-> one RAID6 md0

One physical volume group
logical volume /
logical volume /home

The system does not manage to boot even after going in into the rescue mode and making sure grub is both configured and installed with the lvm module preloading (/etc/default/grub -> update-grub -> grub-install).

It all trips up in grub-pc (GRUB2) somehow and I do not know how to debug it.

GRUB loading.
Welcome to GRUB!

error: file not found.
Entering rescue mode...
grub rescue>


Any pointers? Did I miss and mess up any of the rescue mode superhero stuff?
I tried to wave a rubber chicken and just throw every plausibly connected module at it, but it's still a no-go.

I've seen some indirect talk about mdraid + LVM + EXT4 not being a bootable combo yet, but then again I've seen people boast about their mdraid + dmcrypt + LVM + EXT4 / BTRFS setups.

I guess I will just fall back to a good old fashioned EXT2 boot partition.

Here's my rubber chicken waving approach for the internet:

GRUB_PRELOAD_MODULES="search_fs_uuid raid raid5rec raid6rec mdraid lvm ext2 chain pci"

update-grub

grub-install --modules="search_fs_uuid raid raid5rec raid6rec mdraid lvm ext2 chain pci" /dev/sda