From How do I get a USB thumb drive to boot with grub2?
Thumb drive appears as /dev/sdb
Run these commands
sudo mount /dev/sdb1 /mnt
for i in /dev /dev/pts /proc /sys; do sudo mount -B $i /mnt/$i; done
sudo chroot /mnt
Then edit /boot/grub/grub.cfg
Changed all lines that say (hd1,1) to (hd0,1)
note by acidzombie I ignored what is to the right of the comma and it said sdb for me instead end note
for i in /dev/pts /dev /proc /sys; do sudo umount /mnt/$i ; done
- List item
- Totally power down the server.
- Pull the power cords out. Wait 10s.
- Plug power back in.
- Insert Thumb drive and power on.
- Linux now boots fully from the thumb drive.
It seems that there were two problems. They were to do with having the wrong device referenced in grub.cfg (i.e. hd1 should be hd0).
Secondly, a bug in the server bios. It kept referring to a uuid for a filesystem on a different thumb drive that I'd be earlier playing with. Warm reboot seemed to keep that uuid in there. A cold boot fixed it.