unity grub-install on raid incorrectly handles 'writemostly' flag

[Andrew Fernandes]

Binary package hint: ubiquity

I have three disks for software raid that I have set up as /dev/sd[abc]1. The third disk is slower than the first two, so I have it marked as "writemostly" through mdadm. They are assembled onto raid array /dev/md0.

However, ubiquity tries to guess that the bootloader should be installed on all /dev/sd[abc]. That is fantastically-smart behaviour.

However, when probing the array properties, it gets confused. Output of /var/log/messages is:

Nov 24 02:52:38 ubuntu grub-installer: info: Installing grub on '/dev/sda /dev/sdb writemostly /dev/sdc'
Nov 24 02:52:38 ubuntu grub-installer: info: grub-install supports --no-floppy
Nov 24 02:52:38 ubuntu grub-installer: info: Running chroot /target grub-install --no-floppy --force "/dev/sda"
Nov 24 02:52:40 ubuntu grub-installer: Installation finished. No error reported.
Nov 24 02:52:40 ubuntu grub-installer: info: grub-install ran successfully
Nov 24 02:52:40 ubuntu grub-installer: info: grub-install supports --no-floppy
Nov 24 02:52:40 ubuntu grub-installer: info: Running chroot /target grub-install --no-floppy --force "/dev/sdb"
Nov 24 02:52:42 ubuntu grub-installer: Installation finished. No error reported.
Nov 24 02:52:42 ubuntu grub-installer: info: grub-install ran successfully
Nov 24 02:52:42 ubuntu grub-installer: info: grub-install supports --no-floppy
Nov 24 02:52:42 ubuntu grub-installer: info: Running chroot /target grub-install --no-floppy --force "writemostly"
Nov 24 02:52:44 ubuntu grub-installer: Invalid device `writemostly'.
Nov 24 02:52:44 ubuntu grub-installer: Try `/usr/sbin/grub-setup --help' for more information.
Nov 24 02:52:44 ubuntu grub-installer: error: Running 'grub-install --no-floppy --force "writemostly"' failed.

At this point, I get the graphical "Bootloader install failed" dialog, with "How would you like to proceed?"

The problem is that the "okay" button is always greyed out, and thus the installation hangs/fails.

[Andrew Fernandes (andrew-fernandes)]

I should add that booting also fails since the grub configuration now has a syntax error in it; thus this configuration leads to an unbootable install.

[Colin Watson (cjwatson)]

Thanks, I'll fix this right away for Natty. You should be able to work around this by saying no to the "Install the GRUB boot loader to the master boot record?" question (if you get one) and then editing the "Device for boot loader installation:" list.

[Launchpad Janitor (janitor)]

This bug was fixed in the package grub-installer - 1.57ubuntu2

---------------
grub-installer (1.57ubuntu2) natty; urgency=low

  * Ignore words not beginning with "/dev/" in 'mdadm --detail' output
    (LP: #680751).
 -- Colin Watson <email address hidden> Thu, 09 Dec 2010 12:35:22 +0000