The setup: 8 disks in a mdadm-managed RAID5 array (/dev/md0, made from /dev/sdc through /dev/sdj). One disk (/dev/sdh) is showing SMART errors (increasing pending sector count) so I'm looking to replace it. Additionally, the machine boots from a Revodrive SSD in a PCIe slot that's configured with a RAID0 stripe.
The oddness: mdadm --detail output shows the array as clean, and everything looks to be running well (I can mount, read, write the array without problems). mdadm --examine output for every disk shows an array state of failed.
root@saturn:/backup# cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid5 sdi1 sdj1 sdh1 sdg1 sdf1 sde1 sdd1 sdc1 20511854272 blocks super 1.0 level 5, 64k chunk, algorithm 2 [8/8] [UUUUUUUU] unused devices: <none>
The proc table only shows the mdadm managed array of SATA drives, not the revodrive, which I'd expect as the revodrive RAID should be managed by its own hardware controller.
root@saturn:/backup# mdadm --detail /dev/md0 mdadm: metadata format 01.00 unknown, ignored. /dev/md0: Version : 01.00 Creation Time : Wed Apr 20 10:14:05 2011 Raid Level : raid5 Array Size : 20511854272 (19561.63 GiB 21004.14 GB) Used Dev Size : 5860529792 (5589.04 GiB 6001.18 GB) Raid Devices : 8 Total Devices : 8 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Mon Sep 19 13:42:21 2011 State : clean Active Devices : 8 Working Devices : 8 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K Name : saturn:0 (local to host saturn) UUID : e535a44b:b319927e:4a574c20:39fc3f08 Events : 45 Number Major Minor RaidDevice State 0 8 33 0 active sync /dev/sdc1 1 8 49 1 active sync /dev/sdd1 2 8 65 2 active sync /dev/sde1 3 8 81 3 active sync /dev/sdf1 4 8 97 4 active sync /dev/sdg1 5 8 113 5 active sync /dev/sdh1 6 8 129 6 active sync /dev/sdi1 8 8 145 7 active sync /dev/sdj1
Obviously, there's a metadata format error in the first line, from an auto-generated metadata flag in mdadm.conf, but this is mdadm v126.96.36.199 running on Ubuntu, and I've chalked it down to a known issue
root@saturn:/backup# mdadm --examine /dev/sdc1 mdadm: metadata format 01.00 unknown, ignored. /dev/sdc1: Magic : a92b4efc Version : 1.0 Feature Map : 0x0 Array UUID : e535a44b:b319927e:4a574c20:39fc3f08 Name : saturn:0 (local to host saturn) Creation Time : Wed Apr 20 10:14:05 2011 Raid Level : raid5 Raid Devices : 8 Avail Dev Size : 5860529904 (2794.52 GiB 3000.59 GB) Array Size : 41023708544 (19561.63 GiB 21004.14 GB) Used Dev Size : 5860529792 (2794.52 GiB 3000.59 GB) Super Offset : 5860530160 sectors State : clean Device UUID : 1b508410:b129e871:d92c7979:30764611 Update Time : Mon Sep 19 13:52:58 2011 Checksum : 2e68592 - correct Events : 45 Layout : left-symmetric Chunk Size : 64K Array Slot : 0 (0, 1, 2, 3, 4, 5, 6, failed, 7) Array State : Uuuuuuuu 1 failed
But in the --examine output, the Array state is failed. Each disk seems to show itself as the failed member - /dev/sdd shows u*U*uuuuuu, /dev/sde shows uu*U*uuuuu, etc - but all show the mystery 9th "failed" slot between slots 6 and 7 on the previous line.
I'm guessing the disk superblocks are screwy, despite everything being functional. I'd like to get this fixed before proceeding with the replacement of the suspect disk, as I'm a little concerned about how the disks might behave if I failed a drive. What's the best way for me to proceed?