One of our office servers refused to reboot after a recent update. Attaching a monitor to it we discovered that it could no longer find its boot device. Manually editing grub and changing hda1 to sda1 (its primary SATA drive) caused it to boot successfully. To make the change permanent we applied the following. Alter the /boot/grub/menu.lst file to show the root at sda1 rossetti@Wakatipu:~$ sudo vi /boot/grub/menu.lst rossetti@Wakatipu:~$ grep sda /boot/grub/menu.lst # kopt=root=/dev/sda1 ro Update grub rossetti@Wakatipu:~$ sudo update-grub Searching for GRUB installation directory ... found: /boot/grub warning: grub-probe can't find drive for /dev/sda1. Please check /boot/grub/device.map, you might have to regenerate it with grub-mkdevicemap. Update devicemap rossetti@Wakatipu:~$ cat /boot/grub/device.map (hd0)/dev/hda rossetti@Wakatipu:~$ sudo grub-mkdevicemap rossetti@Wakatipu:~$ cat /boot/grub/device.map (fd0)/dev/fd0 (hd0)/dev/sda (hd1)/dev/sdb Update grub (again) rossetti@Wakatipu:~$ sudo update-grub Searching for GRUB installation directory ... found: /boot/grub Searching for default file ... found: /boot/grub/default Testing for an existing GRUB menu.lst file ... found: /boot/grub/menu.lst Searching for splash image ... none found, skipping ... Found kernel: /boot/vmlinuz-2.6.26-2-686 Found kernel: /boot/vmlinuz-2.6.26-1-686 Found kernel: /boot/vmlinuz-2.6.18-4-686 Updating /boot/grub/menu.lst ... done Check grub and reboot rossetti@Wakatipu:~$ grep sda /boot/grub/menu.lst # kopt=root=/dev/sda1 ro kernel/boot/vmlinuz-2.6.26-2-686 root=/dev/sda1 ro kernel/boot/vmlinuz-2.6.26-2-686 root=/dev/sda1 ro single kernel/boot/vmlinuz-2.6.26-1-686 root=/dev/sda1 ro kernel/boot/vmlinuz-2.6.26-1-686 root=/dev/sda1 ro single kernel/boot/vmlinuz-2.6.18-4-686 root=/dev/sda1 ro kernel/boot/vmlinuz-2.6.18-4-686 root=/dev/sda1 ro single rossetti@Wakatipu:~$ sudo reboot