Rescue mode: cannot fix boot after raid1 repair
List, good afternoon,
We had a raid 1 failure on our (one remaining) Lenny system this
morning, /dev/sda failed, and I've replaced it with a new disk, which
is unformatted and unpartitioned at the moment. We're unable to boot
from the second (original) disk in the machine, /dev/sdb. Guessing
that /dev/sdb doesn't have a boot record (MBR), I tried rescue mode
from a Squeeze install CD, with the intention of (?re-)installing Grub
but I haven't found grub on either our existing root filesystem or in
the installer rescue system. I've also tried various 'rescue' and
'boot' CDs but we couldn't get those to load the root filesystem.
/dev/sdb is partitioned:
sdb1: /boot2 (this was a simple copy of /boot on /dev/sda1; sda1 and
sdb1 were not raid)
sdb2: (raid1) /
sdb3: (raid1) /usr
sdb4: (raid1) /var
sdb5: swap
sdb6: (raid1) /tmp
sdb7: (raid1) /home
sdb8: (raid1) /userdata
Could I ask 3 questions? Is there a way I can check whether there is
a correct MBR on /dev/sdb?
Secondly, /boot on /dev/sda1 had been flagged as bootable, so to boot
from /dev/sdb1 should I now flag /dev/sdb1 as bootable and, if so, how
should I do that from the rescue mode?
Lastly, do I need to run a grub installer and, if so, where ought I be
able to find that? I tried running grub-install from both a shell in
the root filesystem, and from a shell in the rescue system, but
grub-install seemed not to be there. Perhaps the shell needs a 'path'
to find it or, even, some other partitions mounted.
I'm a bit lost and would appreciate any guidance. Provided that I can
fix the boot, we should be ok because the filesystem still seems to be
there and the /userdata is backed up as well.
Ron
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