I've searched the RAID FAQ's, wiki and googled it multiple different ways
but I can't find the E flag in the RAID documentation. I'm using a
synology cs407e appliance with a 2.6.24 kernel. This is what /proc/mdstat
shows:
CubeStation> cat /proc/mdstat
Personalities : [linear] [raid0] [raid1] [raid6] [raid5] [raid4]
md2 : active raid5 sda3[0] sdb3[1] sdc3[2](E)
2188293696 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUE_]
md1 : active raid1 sda2[0] sdb2[1] sdc2[2]
522048 blocks [4/3] [UUU_]
md0 : active raid1 sda1[0] sdb1[1] sdc1[2]
2489920 blocks [4/3] [UUU_]
unused devices: <none>
The backstory is that sdd failed so I was backing up the ext3 filesystem
on md2 when sdc3 had a hiccup. Since mdadm is showing 3 of 4 drives in the
RAID set as active I'm really hoping someone can help me get md2 fully
online so that I can get the data off of it.
The appliance uses mdadm to manipulate the RAID volumes and is short on
other tools. I've tried stopping /dev/md2 and using mdadm -Af /dev/md2
with the UUID below to recover it without luck. (it activates with the E
flag again) Here is more info that will hopefully help determine the next
steps.
CubeStation> mdadm --detail /dev/md2
/dev/md2:
Version : 00.90
Creation Time : Tue Apr 28 02:42:08 2009
Raid Level : raid5
Array Size : 2188293696 (2086.92 GiB 2240.81 GB)
Used Dev Size : 729431232 (695.64 GiB 746.94 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 2
Persistence : Superblock is persistent
Update Time : Tue Nov 24 21:42:24 2009
State : clean, degraded
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 64K
UUID : aa6e4f7b:b441bc58:32d7a109:4c5bf4e2
Events : 0.28604
Number Major Minor RaidDevice State
0 8 3 0 active sync /dev/sda3
1 8 19 1 active sync /dev/hdb3
2 8 35 2 active sync /dev/hdc3
3 0 0 3 removed
CubeStation> mdadm -E /dev/sda3
/dev/sda3:
Magic : a92b4efc
Version : 00.90.00
UUID : aa6e4f7b:b441bc58:32d7a109:4c5bf4e2
Creation Time : Tue Apr 28 02:42:08 2009
Raid Level : raid5
Used Dev Size : 729431232 (695.64 GiB 746.94 GB)
Array Size : 2188293696 (2086.92 GiB 2240.81 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 2
Update Time : Tue Nov 24 21:42:24 2009
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Checksum : 478e9350 - correct
Events : 28604
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 0 8 3 0 active sync /dev/sda3
0 0 8 3 0 active sync /dev/sda3
1 1 8 19 1 active sync /dev/hdb3
2 2 8 35 2 active sync /dev/hdc3
3 3 0 0 3 faulty removed
CubeStation> mdadm -E /dev/sdb3
/dev/sdb3:
Magic : a92b4efc
Version : 00.90.00
UUID : aa6e4f7b:b441bc58:32d7a109:4c5bf4e2
Creation Time : Tue Apr 28 02:42:08 2009
Raid Level : raid5
Used Dev Size : 729431232 (695.64 GiB 746.94 GB)
Array Size : 2188293696 (2086.92 GiB 2240.81 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 2
Update Time : Tue Nov 24 21:42:24 2009
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Checksum : 478e9362 - correct
Events : 28604
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 1 8 19 1 active sync /dev/hdb3
0 0 8 3 0 active sync /dev/sda3
1 1 8 19 1 active sync /dev/hdb3
2 2 8 35 2 active sync /dev/hdc3
3 3 0 0 3 faulty removed
CubeStation> mdadm -E /dev/sdc3
/dev/sdc3:
Magic : a92b4efc
Version : 00.90.00
UUID : aa6e4f7b:b441bc58:32d7a109:4c5bf4e2
Creation Time : Tue Apr 28 02:42:08 2009
Raid Level : raid5
Used Dev Size : 729431232 (695.64 GiB 746.94 GB)
Array Size : 2188293696 (2086.92 GiB 2240.81 GB)
Raid Devices : 4
Total Devices : 3
Preferred Minor : 2
Update Time : Tue Nov 24 21:42:24 2009
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 1
Spare Devices : 0
Checksum : 478e93b4 - correct
Events : 28604
Layout : left-symmetric
Chunk Size : 64K
Number Major Minor RaidDevice State
this 2 8 35 2 active sync /dev/hdc3
0 0 8 3 0 active sync /dev/sda3
1 1 8 19 1 active sync /dev/hdb3
2 2 8 35 2 active sync /dev/hdc3
3 3 0 0 3 faulty removed
CubeStation> mount -t ext3 -o ro /dev/md2 /volume1
mount: Mounting /dev/md2 on /volume1 failed: Invalid argument
CubeStation> tail /var/log/messages
Nov 25 00:48:08 kernel: md: md2: set sda3 to auto_remap [0]
Nov 25 00:48:08 kernel: md: md2: set sdc3 to auto_remap [0]
Nov 25 00:48:08 kernel: md: md2: set sdb3 to auto_remap [0]
Nov 25 00:48:08 kernel: raid5: raid level 5 set md2 active with 3 out of 4
devices, algorithm 2
Nov 25 00:48:08 kernel: RAID5 conf printout:
Nov 25 00:48:08 kernel: --- rd:4 wd:3
Nov 25 00:48:08 kernel: disk 0, o:1, dev:sda3
Nov 25 00:48:08 kernel: disk 1, o:1, dev:sdb3
Nov 25 00:48:08 kernel: disk 2, o:1, dev:sdc3
Nov 25 00:49:07 kernel: EXT3-fs: can't read group descriptor 47
Thank you for helping!
Brian
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