On 6/1/2014 6:15 PM, Mark Mitchell wrote:: > I built my first RAID array about a week ago, kinda vaguely > understanding what I'm doing. 4 3 TB drives in a RAID 5. It's been > working fine, and I've been slowly filling it up. > > Took the machine apart today to upgrade case cooling and power supply. > When I brought it back up, I got this in the boot messages; > > md/raid:md0: raid level 5 active with 3 out of 4 devices, algorithm 2 > > My 1st thought was that I didn't get everything hooked up (I had to > disconnect most of the drives to get the power connections on the > board), several reboots later, I'd confirmed that the system was > seeing all the drives; > > root at debian:/var/log# lsblk > NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT > sda 8:0 0 931.5G 0 disk > ├─sda1 8:1 0 14G 0 part / > ├─sda2 8:2 0 37.3G 0 part [SWAP] > └─sda3 8:3 0 880.3G 0 part /home > sdb 8:16 0 2.7T 0 disk > └─sdb1 8:17 0 2.7T 0 part > └─md0 9:0 0 8.2T 0 raid5 > └─md0p1 259:0 0 8.2T 0 md /srv/media > sdc 8:32 0 2.7T 0 disk > └─sdc1 8:33 0 2.7T 0 part > sdd 8:48 0 2.7T 0 disk > └─sdd1 8:49 0 2.7T 0 part > └─md0 9:0 0 8.2T 0 raid5 > └─md0p1 259:0 0 8.2T 0 md /srv/media > sde 8:64 0 2.7T 0 disk > └─sde1 8:65 0 2.7T 0 part > └─md0 9:0 0 8.2T 0 raid5 > └─md0p1 259:0 0 8.2T 0 md /srv/media > sr0 11:0 1 7.3G 0 rom > > So, it looks like the partition on sdc isn't being seen as a raid > partition anymore. > > FWIW; > root at debian:/var/log# cat /proc/mdstat > Personalities : [raid6] [raid5] [raid4] > md0 : active raid5 sdb1[0] sde1[4] sdd1[2] > 8790405120 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/3] [U_UU] > bitmap: 4/22 pages [16KB], 65536KB chunk > > unused devices: <none> > > So, what's my next step? Looks to me like I need to recreate sdc1 as > a raid partition, then regrow the array. Is this correct? > > In the meantime, I'm reading what I can and copying data off the > array. Nothing critical, but it'd be annoying to lose. > > Let me know if I left out required information. > do a mdadm --detail /dev/md0 (or md* for all), and look for the failed device\partition# *Adjust the below to your config* First fail the drive sudo mdadm /dev/md0 -f /dev/sdc1fdisk /dev/sdb Then remove the drive sudo mdadm /dev/md0 -r /dev/sdc1 To re-add an out of sink partition I just "sudo mdadm --manage --re-add /dev/md0 /dev/sdc1" To check rebuilt status watch cat /proc/mdstat Done. Good Luck!