Earlier I was trying to mount one disk of a RAID 1 mirrored-set but was having no joy. After a long time searching I eventually found...
john@jupiter64:~$ sudo mdadm --assemble /dev/md0 /dev/sda1
mdadm: /dev/md0 assembled from 1 drive - need all 2 to start it (use --run to insist).
So trying it again with --run added....
john@jupiter64:~$ sudo mdadm --assemble /dev/md0 /dev/sda1 --run
mdadm: /dev/md0 has been started with 1 drive (out of 2).
Also if your planning to shift a lot of files across a LAN to a home server, try using FTP rather than SMB/CIFS. The former gives me around 100MB/s whereas the latter was averaging 60MB/s. Can make a big time saving when moving GBs of data. #mdadm #RAID1 #degraded