Software RAID5 recovery from HDD failure (FC2), help

[nick ristow]

Hi,

I just had a drive failure on a RAID 5 array. Its made up of 3 250gig 
hdds, each with 1 partition covering the whole disk. One of the hdds 
has failed and I'm trying to get the partition back up long enough that 
i can either use a spare disk to recover, or backup all my data and 
start over.

The problem I'm running into is when the raid driver has seen that the 
disk is bad, and sets it as failed it appears that the system stops 
working. USB devices are unresponsive, networking is unresponsive and 
the startup scripts don't finish running.

When I boot with a replacement disk in place of the original hdg (its a 
300gig maxtor), I get an error on startup that /dev/md0 is 'not a 
linear or raid0' array, that there was an error and its dropping me to 
a shell. The array isn't running so I can't 'raidhotadd' the new drive 
to it. I havn't seen anything in the howto on how to restore the array 
when its offline. I've never used mdadm, so I'm not sure if that is the 
part I'm missing or what.

  It seems like I should be able to restore from the 2 existing good 
drives, I must be missing something. If more info is needed, I can get 
error logs and other output.