July 5th, 2007

belize

Unexpected failure mode

Dear Lazyweb,

Let's imagine for a second, hypothetically, that some drunk girl sees Blinkenlights on the RAID array in your garage and says (reportedly) "Oh neat, hot swap!", and proceeds to remove 3 drives from a particular 5-disk RAID-5 array, instantly killing the party music and a quite a bit of other data [accessibility].

Hypothetically, that would look like this: (after a reboot, incidentally)
# cat /proc/mdstat 
Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4] 
md1 : inactive sda[0] sde[4] sdd[3] sdc[2] sdb[1]
      2441932480 blocks super non-persistent
       
md0 : active raid1 sdf1[0] sdg1[1]
      97659008 blocks [2/2] [UU]
      
unused devices: <none>

Since I'm currently in Grass Valley for nick's wedding, enjoying the ~110F heat (it was 113F/45C on the way up here!), I'll leave it to you guys, my friendly LazyWeb, to suggest how one might fix such a busted array, perhaps saving me some time reading mdadm(8).

Lovingly yours,
Brad