How to recover mdadm raid6 array? mount: can't read superblock. 8/13 drives show all drives present, 5/13 drives show only 5 drives present
I rebooted my server today to find it hanging. I commented out the entry in fstab that loads /dev/md0 and the machine proceeded to boot. The raid was accessible and working prior to the reboot, I only rebooted because of system updates.
The server motherboard is Supermicro X9SAE, and the system has 14 disks, 1 SSD boot drive and 13 disks in a raid6 array. 5/13 disks in the array are attached to the onboard Sata. 8/13 disks in the array are attached to an IT mode LSI 9211-8i
sudo fdisk -l shows all 13 drives, and all 13 drives pass smart tests
tried to mount manually from the command line:
sudo mount /dev/md0 /mnt/md0
mount: /mnt/md0: can't read superblock on /dev/md0.
cat /proc/mdstat
md0 : inactive sdh[13](S) sdc[8](S) sdm[0](S) sdb[7](S) sdj[14](S) sdd[9](S) sdk[5](S) sdg[12](S) sda[6](S) sdn[2](S) sdl[1](S) sde[10](S) sdf[11](S)
76185162872 blocks super 1.2
Next I tried:
sudo mdadm --stop /dev/md0
mdadm: stopped /dev/md0
sudo mdadm --assemble /dev/md0 /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh /dev/sdj /dev/sdk /dev/sdl /dev/sdm /dev/sdn
mdadm: /dev/md0 assembled from 5 drives - not enough to start the array.
I thought it was odd that it tried 5 drives which is how many is attached to the onboard, sdj-sdn. So I tried assemble with just the ones on the card:
sudo mdadm --assemble /dev/md0 /dev/sda /dev/sdb /dev/sdc /dev/sdd /dev/sde /dev/sdf /dev/sdg /dev/sdh
mdadm: /dev/md0 assembled from 8 drives - not enough to start the array.
By doing it that way it tried to assemble from 8 drives. So it seems like the 5 onboard disks are out of sync with the 8 drives attached to the card, but this is purely a guess. Next I examined each drive.
This next bit will be pretty long, its the mdadm --examine details of all 13 drives. The thing that I noticed here is that drives sda-sdh all show all disks as present, but drives sdj-sdn show 8 drives missing for the Array State, also noticed the event count, the onboard drives have Events : 1913088, while the ones on the card are at 1913085:
sudo mdadm --examine /dev/sda
/dev/sda:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 344864e7:5e19631d:0b14d41f:58264c67
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : 447ce0e - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 12
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdb
/dev/sdb:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 244b3058:6919fa6f:c2499e3d:fb9db6e1
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : 5fdf7e64 - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 11
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdc
/dev/sdc:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 9081b898:7782d040:acdcc700:e8621ca2
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : f4cd75b5 - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 10
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdd
/dev/sdd:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 1b569018:549dae95:bbd59910:601886e3
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : 1abf13a6 - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 9
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sde
/dev/sde:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 534b24a4:63d20861:502e4012:53fe2652
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : e1f47c75 - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 8
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdf
/dev/sdf:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 0821860a:7b75d1cc:bb512247:3dc34a12
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : a924dd98 - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 7
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdg
/dev/sdg:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 0c870013:b577639c:eba5f8d4:10a5fee4
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : e1bb7bdb - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 6
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdh
/dev/sdh:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : 06713ac7:ab2a7de0:d6e0d447:52ed0231
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:38 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : 98ef9bf9 - correct
Events : 1913085
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 5
Array State : AAAAAAAAAAAAA ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdj
/dev/sdj:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250800 sectors, after=11440 sectors
State : clean
Device UUID : d6fb6b75:18fee031:84b97ab4:43ee3754
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:43 2019
Bad Block Log : 512 entries available at offset 32 sectors
Checksum : 283bd3b6 - correct
Events : 1913088
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 3
Array State : AAAAA........ ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdk
/dev/sdk:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250792 sectors, after=11440 sectors
State : clean
Device UUID : aa02fdc1:15332b2a:eee48dee:9d6a91df
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:43 2019
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 3283b76b - correct
Events : 1913088
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 4
Array State : AAAAA........ ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdl
/dev/sdl:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250792 sectors, after=11440 sectors
State : clean
Device UUID : 4701d341:4c70e117:8a8d37a0:19f8b474
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:43 2019
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : e6dd2971 - correct
Events : 1913088
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 1
Array State : AAAAA........ ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdm
/dev/sdm:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250792 sectors, after=11440 sectors
State : clean
Device UUID : ab1c4435:3c735172:3cf07404:f66f2944
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:43 2019
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 68702233 - correct
Events : 1913088
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 0
Array State : AAAAA........ ('A' == active, '.' == missing, 'R' == replacing)
sudo mdadm --examine /dev/sdn
/dev/sdn:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Raid Devices : 13
Avail Dev Size : 11720794288 (5588.91 GiB 6001.05 GB)
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 11720782848 (5588.90 GiB 6001.04 GB)
Data Offset : 250880 sectors
Super Offset : 8 sectors
Unused Space : before=250792 sectors, after=11440 sectors
State : clean
Device UUID : b7465e3e:502defd4:dcf61288:b0f14a84
Internal Bitmap : 8 sectors from superblock
Update Time : Thu Apr 18 09:07:43 2019
Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 97e78eb0 - correct
Events : 1913088
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : AAAAA........ ('A' == active, '.' == missing, 'R' == replacing)
THIS IS FROM April 17th when it was still working:
/dev/md0:
Version : 1.2
Creation Time : Sat Nov 5 18:56:32 2016
Raid Level : raid6
Array Size : 64464305664 (61477.95 GiB 66011.45 GB)
Used Dev Size : 5860391424 (5588.90 GiB 6001.04 GB)
Raid Devices : 13
Total Devices : 13
Persistence : Superblock is persistent
Intent Bitmap : Internal
Update Time : Tue Apr 16 19:14:14 2019
State : clean
Active Devices : 13
Working Devices : 13
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Consistency Policy : bitmap
Name : ubuntu:0 (local to host ubuntu)
UUID : 405dae60:c540c726:087bbaaf:a15c79c5
Events : 1913085
Number Major Minor RaidDevice State
0 8 192 0 active sync /dev/sdm
1 8 176 1 active sync /dev/sdl
2 8 208 2 active sync /dev/sdn
14 8 144 3 active sync /dev/sdj
5 8 160 4 active sync /dev/sdk
13 8 112 5 active sync /dev/sdh
12 8 96 6 active sync /dev/sdg
11 8 80 7 active sync /dev/sdf
10 8 64 8 active sync /dev/sde
9 8 48 9 active sync /dev/sdd
8 8 32 10 active sync /dev/sdc
7 8 16 11 active sync /dev/sdb
6 8 0 12 active sync /dev/sda
What should be my next step to bring the array back online?
HERE IS WHAT I DID, Array is back online and appears to be working. Strangely the last message was "not enough to start the array." but it did start and after a reboot the array is active and clean, and all event counts match. There might be a small amount of data corruption someplace, but the system had been idle for days without issue so I doubt its anything I will miss.
Will keep a close eye on the system for a while, as well as the event counts.
sudo mdadm --stop /dev/md0
sudo mdadm --assemble --scan --force
mdadm: forcing event count in /dev/sdh(5) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sdg(6) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sdf(7) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sde(8) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sdd(9) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sdc(10) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sdb(11) from 1913085 upto 1913088
mdadm: forcing event count in /dev/sda(12) from 1913085 upto 1913088
mdadm: clearing FAULTY flag for device 0 in /dev/md0 for /dev/sdh
mdadm: clearing FAULTY flag for device 1 in /dev/md0 for /dev/sdg
mdadm: clearing FAULTY flag for device 3 in /dev/md0 for /dev/sdf
mdadm: clearing FAULTY flag for device 2 in /dev/md0 for /dev/sde
mdadm: clearing FAULTY flag for device 4 in /dev/md0 for /dev/sdd
mdadm: clearing FAULTY flag for device 5 in /dev/md0 for /dev/sdc
mdadm: clearing FAULTY flag for device 6 in /dev/md0 for /dev/sdb
mdadm: clearing FAULTY flag for device 7 in /dev/md0 for /dev/sda
mdadm: Marking array /dev/md0 as 'clean'
mdadm: /dev/md0 assembled from 13 drives - not enough to start the array.