recreating a software RAID 5 array
I'm running Debian/Squeeze on a machine that is more like a server than a desktop. Everything is onboard except for the 5 x 500G SATA drives and the DVD rewriter. Phenom II 940 with 4G ram.
I'm not sure what happened. Sometime between Friday evening and Saturday morning my machine locked up. When I reset it, two of the three RAID arrays on it didn't come up. /dev/md0 is /boot and it is RAID 1. It started OK but could only get me into busybox.
/dev/md1 reported 4 out of 5 drives OK so when I started it and added the missing drive back in, it started rebuilding. Three hours later, at 100% rebuilt, it suddenly spewed out a pile of error messages. After that it only showed 3 out 5 drives as OK.
/dev/md2 only shows 3 out 5 drives OK.
I've been working from an Ubuntu Karmic live CD for the rest of this:
According to smartctl, all the drives are OK. I'd guess that the problem relate to the the superblock and that the data is most likely OK if the superblocks can be repaired.
I've been working with /dev/md2 since it is the (replaceable) system drive (/). I figured if I could reassemble the array with 4 out the 5 drives, I should be able to mount it. Unfortunately, that doesn't seem to be the case. No combination/order of component devices seems to give me back a mountable partition.
Since it's dispensable, I've also tried recreating the /dev/md2 array with the same results. I wrote a script to cycle through the combinations of drives to build an array with and without a missing drive and I still can't it to mount.