After upgrading my Raid1 disks for a larger capacity, I ran into some boot problems, so here’s some notes for next time:
- Ubuntu Alternate install USB boot is great for booting into a rescue environment.
- Create a Multiboot USB key with MultiBootISOs
- Ubuntu’s Single User (Rescue mode) isnt that good, as the system needs to be able to boot to get to it (see below)
- If you change anything to do with FS uuid or MD uuid: update-grub and grub-install and edit fstab.
- List UUID’s for each partition / Disk: Â ‘ls -l /dev/disk/by-uuid ‘
- Update MDADM: Â Â ‘mdadm –examine –scan >> /etc/mdadm/mdadm.conf’
- If booting hangs at mounting partitions from fstab, press ‘s’ to skip or ‘m’ for maintenance (why un-documented?)
- Kernel Boot Options, to drop to shell add ‘break’ for early exit or ‘break=init’ or ‘break=mount’ and bootdegraded=true for missing drives
- Grub2 needs to ‘insmod’ the following: ‘raid’, ‘mdraid’, ‘lvm’ then use ‘ls’ to list devices or their partition (uuid) info.
- To re-install Grub(2) from the installer shell, mount –bind sys,dev,proc to target before the chroot, and make sure var & root & boot is mounted rw?
# mount /dev/md1 /target/ Â Â Â Â #? installer\Rescue disk should have done this already
mount –bind /dev/ /target/dev/
mount –bind /sys/ /target/sys/
mount –bind /proc/ /target/proc/
chroot /targetgrub-install –no-floppy –modules=raid /dev/sda
grub-install –no-floppy –modules=raid /dev/sdb
update-grub
