[mythtv-users] Reassemble RAID with mdadm

[George Mari]

On 03/16/2010 05:02 AM, Phillip Barnett wrote:
> I have three disks, sda, sdb, sdc. The OS is on sda, and sdb and sdc
> were RAIDed as RAID1, with all my media.
>
> Recently my myth installation got totally screwed up, and I decided to
> do a complete upgrade/reinstall. However, this has now broken the array
> as all the config material was on the sda drive (d'oh!), and I need to
> know how to reassemble the disks. Using mdadm --create didn't work, as
> it warned me that the disks were already used for an array. Should I use
> assemble, create or build in this instance? The disks themselves are
> intact and can be mounted and read individually, but I do need to
> reassemble them into a RAID without losing the media already on them.
>

What is the output of cat /proc/mdstat?

If your sdb and sdc drives are listed in there as part of an array, all 
you would have to do is mount the array to the mountpoint you desire.

If they aren't part of an array, you should just be able to use the 
mdadm --assemble command to asseble the two drives into an array.

However, if they are not auto-assembling after a reboot, then most 
likely this assembly will only work temprorarily.  You may need to look 
into your /etc/mdadm.conf file to see how the arrary was identified 
previously, and figure out why it's no longer being identified.  I've 
had the UUID of the array change as part of a system upgrade before, 
which was annoying, but fixable.