New computer, same RAID. MDADM won't assemble

Question

Ubuntu 12.04 64. Hardware failure (motherboard) led me to build a new machine, and I took the opportunity to do a fresh install of Ubuntu (first one was a learning experience). I moved the raid disks over and am seeing them in Disk Utility as /dev/sdb and /dev/sdc with their volumes listed as "RAID Component".

However, when I try to mount them like so

sudo mdadm --assemble /dev/md0 /dev/sdb /dev/sdc

I get this error

mdadm: Cannot assemble mbr metadata on /dev/sdb
mdadm: /dev/sdb has no superblock - assembly aborted

Any ideas?

Answer 1

Solution: I followed the instructions found here: Move RAID1 to new machine

In effect, I had to disconnect the drives during the installation process, then the system detected them properly once it was up and running.

Answer 2

The problem may have been not addressing the RAID partitions on the devices instead of the device. Using:

mdadm --examine /dev/sdb
mdadm --examine /dev/sdb1

you can check for which superblock is the one you want for your raid.

Then, you have to choose the actual block, e.g.:

mdadm --assemble /dev/md0 /dev/sdb2 /dev/sdc2