I have a box with Ubuntu 12.04, and just did a apt-get upgrade. I'm presented with a dialogue to update my GRUB bootloader, but with the following message:

The GRUB boot loader was previously installed to a disk that is no longer present,
or whose unique identifier has changed for some reason. It is important to make sure that the
installed GRUB core image stays in sync with GRUB modules and grub.cfg. Please check
again to make sure that GRUB is written to the appropriate boot devices.

If you're unsure which drive is designated as boot drive by your BIOS, it is often 
a good idea to install GRUB to all of them.

Note: it is possible to install GRUB to partition boot records as well, and some
appropriate partitions are offered here. However, this forces GRUB to use the blocklist
mechanism, which makes it less reliable, and therefore is not recommended.

GRUB install devices:
[ ] /dev/sda (3000592 MB; ST3000DM001-9YN166)
[ ] /dev/sdb (3000592 MB; ST3000DM001-9YN166)
[ ] /dev/md1 (536 MB; rescue:1)
[ ] /dev/md2 (1099510 MB; rescue:2)

I'm worried that choosing the wrong option will render my box unbootable. I don't have physical access to it, as it's a box in a cloud. Please advice!


This is my /etc/fstab:

proc /proc proc defaults 0 0
/dev/md/0 none swap sw 0 0
/dev/md/1 /boot ext3 defaults 0 0
/dev/md/2 / ext4 defaults 0 0
/dev/md/3 /home ext4 defaults 0 0

This is my df -h:

Filesystem      Size  Used Avail Use% Mounted on
/dev/md2       1016G  127G  838G  14% /
udev             16G  4.0K   16G   1% /dev
tmpfs           6.3G  768K  6.3G   1% /run
none            5.0M     0  5.0M   0% /run/lock
none             16G     0   16G   0% /run/shm
/dev/md1        496M   44M  427M  10% /boot
/dev/md3        1.7T  368G  1.3T  23% /home
  • 1
    Well how are your disks partitioned, and how are they configured? Using /dev/md1,/dev/md2 is probably the wrong choice. But without more information anything we say would be a random guess. Look at your fstab, look at how grub was configured before you started the install. Look at how your physical drives are partitioned... – Zoredache Jan 17 '14 at 18:47
  • how do i do that exactly? any cmd's i can dump here? thanks – knutole Jan 17 '14 at 19:34
  • Do you know why this problem arises in the first place, btw? – knutole Jan 17 '14 at 19:41
  • @Zoredache added some more info. PLEASE help! :) – knutole Jan 17 '14 at 20:24
  • 1
    Do you know why this problem arises in the first place, btw? - Because how the kernel named IDE devices changed when some IDE/SATA drivers were changed. So a device that was previously /dev/hda is now /dev/sda. – Zoredache Jan 17 '14 at 22:02

FYI: I got through it ok. In my setup, I installed GRUB on both /dev/sda and /dev/sdb, and it worked swimmingly.

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