Thanks for the great article. This seems to be the best case scenario for a drive failure in a mirrored RAID array (i.e. drive 2 failing in a 2 drive mirror).

Perhaps a useful addition to the article would be to detail how to recover when the first drive (e.g. /dev/sda in this article) fails. Physically removing /dev/sda would allow the system to run from /dev/sdb (so long as the boot loader was installed on /dev/sdb!), but if you put a new HD in /dev/sda, I don't think you would be able to reboot...

You would probably need to remove /dev/sda, then move /dev/sdb to /dev/sda, and then install a new /dev/sdb.