Ok first of all all of this is an assumption so I know what to expect when a RAID 5 Array that I have actually degrades and I have to recover it and I don't have to spend countless hours desperately looking for answers, so here it goes.

Assuming I have a 3 Disk RAID 5 Array set up, what would the correct procedure to recover from 1 disk failing and the array getting degraded?

So far this is what I understand from a couple hours of research:
1. Fail the drive from the array and remove it using mdadm.
2. Then insert the spare
3. ???
4. Add it to the array

The middle part gets a big ambiguous, do I need to do anything with the spare drive at hand, any formating or special commands that I need to run on it.

Like I said I want to have a clear picture before this actually happens and I start to go insane looking for answers.

Thanks in advance!

BTW. This would all be on a Ubuntu Server 11.04 Install, the RAID was set up with the installer and there is no LVM on the RAID, just formated with ext4 on top.