On Tue, Apr 8, 2008 at 1:25 PM, Michael Tokarev <mjt@xxxxxxxxxx> wrote: > > Sean H. wrote: > > > To preface, I'm a fairly new Linux user, and have little experience > > with RAID. I've taken this question several places and have yet to get > > an answer which solves my problem, so I figured I'd come to the > > experts. > > > > I have a five-disk RAID 5, and one of the disks is failing. Every few > > days it'll start buzzing, and will continue buzzing until the drive is > > forced to spin down and back up, by either a restart or suspending to > > RAM. > > > > Now, today, I wanted to determine which disk was failing, so I > > unmounted my array and unplugged drives - Specifically, three. The > > third was the culprit, and I plugged the drives back in and rebooted. > > > > The gift, or in this case, curse of my motherboard is that it > > supports hot-swapping of SATA drives. So the drives didn't just > > disappear inside the OS and reappear after a reboot. They disappeared > > and re-appeared in the OS with incorrect /dev/sd* locations, and then > > I rebooted. > > > > I was unable to boot until I removed the line detailing the array > > from my fstab. Now, when I manually 'mdadm --assemble /dev/md0' mdadm > > finds the two untouched drives, then stops and tells me that they're > > not enough to start the array. > > > > So... How can I reassemble the array without knowing what order the > > drives are in? > > > > Don't list individual component devices in mdadm.conf. > Use array UUIDs instead. > > I.e., instead of: > > --- WRONG --- > ARRAY /dev/md1 devices=/dev/sda1,/dev/sdb1,/dev/sdc1 > --- WRONG --- > > use this: > > --- RIGHT --- > ARRAY /dev/md1 UUID=11111111:22222222:33333333:44444444 > --- RIGHT --- > > Or use modern ways to assemble the arrays - such as homehost > (requires version 1 superblock). > > In either case mdadm will find the relevant components (assuming > DEVICE line in mdadm.conf is correct) and figure out the right > order. > > /mjt > My mdadm.conf is configured with UUIDs: # mdadm.conf written out by anaconda DEVICE partitions MAILADDR root ARRAY /dev/md0 level=raid5 num-devices=5 uuid=58dcdaf3:bdf3f176:f2dd1b6b:f095c127 Tried the following: 'mdadm --assemble /dev/md0 --uuid 58dcdaf3:bdf3f176:f2dd1b6b:f095c127' ... and got this: mdadm: /dev/md0 assembled from 2 drives - not enough to start the array. (Which is what I've been getting for a while, now.) It's possible to correct this issue by unplugging the three drives and plugging them back in and rebooting, so the drives get their original /dev/sd* locations, is it not? (Even if it it possible, I'd like to learn how to fix problems like this at the software level over the hardware level.) -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
