linux raid question

Hi guys, I was wondering, if I have a machine running two discs in a kernel based raid-1, and one of the discs go south, what are the steps involved in removing the one disc and getting the other one up and running again? Just change the fstab entries? Then, if I have an identical disc as a replacement (say I was smart enough to buy three discs and keep one for incase ;-) how do I go about adding the second disc and creating a new raid without putting the installation and data on the good disc in any danger? Thanks -- Kind Regards Hans du Plooy SagacIT (Pty) Ltd hansdp at sagacit dot com