On Sunday January 29, blata@xxxxxxxxxxxx wrote:
> >
> > What exactly are you trying to achieve?
> >
> > NeilBrown
> >
> I live in California and this server is in Ohio ~3000 mi away. Any way I
> am rebuilding it remotely do some problems from a few months ago. Anyway I
> had someone in Ohio format the four drives. I was then left with a system
> on drives a and e. Now after the fact I'm trying to get the software raid
> working on a-c e-g. but I am unable to do so using mdadm. I'm trying to
> coordinate this with my Ohio counterpart when he is available.
>
> At this point I am thinking that I need to have him boot the box into
> rescue mode issue the mdadm commands, edit the fstab file and then reboot.
> Does this sound like a feasible approach?
Feasible, but maybe not ideal.
If you have an active root filesystem on 'a' and want to have it on a
mirrored pair 'a' and 'c', the normal approach, which I'm sure is
documented in some HowTo somewhere - look for "linux root raid" or
similar - is to:
1/ create the mirrored pair with only one active device:
mdadm --create /dev/md0 -l1 -n2 missing /dev/hdc1
2/ create a filesystem there and copy the data over
mkfs -j /dev/md0
mount /dev/md0 /mnt
cp -ax / /mnt
3/ Arrange that you will boot of md0 at next boot.
e.g. in lilo.conf
append = "md=0,/dev/hdc1 root=/dev/md0"
4/ reboot, and hopefully find yourself with /dev/md0 as root.
5/ add the old root partition into the array
mdadm /dev/md0 --add /dev/hda1
6/ make sure hda1 gets included in future. e.g.
change the lilo.conf line to
append = "md=0/dev/hda1,/dev/hdc1 root=/dev/md0"
Good luck.
NeilBrown
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