Problems with raidhotadd (mdadm --add)

[richb at pioneer.ci.net (Rich Braun)]

Doug Sweetser wrote:
> I am the last step away from having RAID-1, but the command:
> 'raidhotadd /dev/md0/ /dev/hda6' fails because hda6 has inodes busy
> from booting using grub.

Thanks for giving RAID as try!

I don't see how the above explanation could be true--grub can't keep a file
open all the way through a system boot--but I can't dream up an alternative
explanation either.  In any event--from your 'df' list, I see that you have a
separate boot partion on /dev/hda1.  Why boot off /dev/hda6?  How about
booting off hda1 instead?  Get the root filesystem working before trying to
tackle the boot partition (which you'd then set up as a separate /dev/md1 RAID
filesystem).

Simply do a 'grub-install --root-directory=/boot /dev/hda' (with /dev/hda1
mounted as /boot), make sure /dev/hda6 is the same size as /dev/hdc6 and that
its partition type is fd, reboot off /dev/hda1, and then your raidhotadd (or
rather 'mdadm --add /dev/md0 /dev/hda6') should work the same as it did on my
system.

I didn't feel the need to set up a RAID boot fs; I'm satisfied just having
grub in the mbr of each of the two disks (just do a grub-install onto each,
plus a backup CD or floppy), and a relatively recent copy of the /boot layout
of my 2.4.22 kernel in a small partition of each.  Test your installation, of
course, by disabling each drive in turn to make sure you can boot up easily in
the event of a failure of either.

Write back and let us know if you've solved it and/or need some more help.

-rich