Ah, sorry, was just frustrated. Think I got it. It's a RAID5 with 3 drives. I think I'm running a hardware RAID too. I managed to get a bit of life back into the bad drive and left it rebuilding over night. Gonna quickly back it up as soon as it's finished. Still not sure how I'm supposed to recover my data with only 2 of the 3 drives but it looks like I won't have to.
data on a raid5 volume with n-1 disks should still be accessible (albeit, with a performance penalty) without having to do anything.
if you can't, i'd seriously question my configuration.
with a software raid, evicting the failed disk and replacing it with a new one will likely require user interaction.