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Can't mount /dev/md0 Raid5

DISCUSSION Joseba Ibarra 2 participants 2 messages Sep 22, 2017 – Sep 27, 2017 MD RAID

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Joseba Ibarra

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Hi.I have a RAID5 using 4 drives in a HO Proliant G8 Microserver

I got a Proxmox installed and the disks for RAID are associated with a specific VM with Debian 9. It worked like a charm.

But, some days ago i broke a proccess giving some permissions (sudo chmod....) to some folders into of the mounted /dev/md0. Then after restart the VM the RAID din't mount again. The raid contents very important data for me, so i'm not very sure what to do in order don't lose the data. So, i´m getting bit panic.

I need some guide to rebuild the system without losing the content.

mdadm version is 3.4-4+b1

This is the result of the fdisk -l related with the RAID

root@grafico:/# fdisk -l
Disco /dev/sdb: 931,5 GiB, 1000204886016 bytes, 1953525168 sectores
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 512 bytes
Tamaño de E/S (mínimo/óptimo): 512 bytes / 512 bytes
Tipo de etiqueta de disco: dos
Identificador del disco: 0x087383f0

Disposit. Inicio Comienzo Final Sectores Tamaño Id Tipo
/dev/sdb1 2048 1953523711 1953521664 931,5G fd Linux raid autodetect

Disco /dev/sdd: 931,5 GiB, 1000204886016 bytes, 1953525168 sectores
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 512 bytes Tamaño de E/S (mínimo/óptimo): 512 bytes / 512 bytes Tipo de etiqueta de disco: dos
Identificador del disco: 0x8b48be4a

Disposit. Inicio Comienzo Final Sectores Tamaño Id Tipo
/dev/sdd1 2048 1953523711 1953521664 931,5G fd Linux raid autodetect

Disco /dev/sdc: 931,5 GiB, 1000204886016 bytes, 1953525168 sectores
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 512 bytes Tamaño de E/S (mínimo/óptimo): 512 bytes / 512 bytes Tipo de etiqueta de disco: dos
Identificador del disco: 0x87ea0d19

Disposit. Inicio Comienzo Final Sectores Tamaño Id Tipo
/dev/sdc1 2048 1953523711 1953521664 931,5G fd Linux raid autodetect

Disco /dev/sde: 931,5 GiB, 1000204886016 bytes, 1953525168 sectores
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 512 bytes Tamaño de E/S (mínimo/óptimo): 512 bytes / 512 bytes Tipo de etiqueta de disco: dos
Identificador del disco: 0xa69b0d7f

Disposit. Inicio Comienzo Final Sectores Tamaño Id Tipo
/dev/sde1 2048 1953523711 1953521664 931,5G fd Linux raid autodetect

Disco /dev/md0: 2,7 TiB, 3000206622720 bytes, 5859778560 sectores
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 512 bytes Tamaño de E/S (mínimo/óptimo): 524288 bytes / 1572864 bytes Tipo de etiqueta de disco: gpt
Identificador del disco: A87C8BBF-5876-4FA6-83F6-46DAF1BDCF75

Disposit. Comienzo Final Sectores Tamaño Tipo
/dev/md0p1 2048 5859776511 5859774464 2,7T Sistema de ficheros de Linux

And here some more information (as you can see the /dev/sde drive have some bad blocks)

root@grafico:/# mdadm --examine /dev/sdb
/dev/sdb:
   MBR Magic : aa55
Partition[0] :   1953521664 sectors at         2048 (type fd)
root@grafico:/# mdadm --examine /dev/sdc
/dev/sdc:
   MBR Magic : aa55
Partition[0] :   1953521664 sectors at         2048 (type fd)
root@grafico:/# mdadm --examine /dev/sdd
/dev/sdd:
   MBR Magic : aa55
Partition[0] :   1953521664 sectors at         2048 (type fd)
root@grafico:/# mdadm --examine /dev/sde
/dev/sde:
   MBR Magic : aa55
Partition[0] :   1953521664 sectors at         2048 (type fd)
root@grafico:/# mdadm --examine /dev/sdb1
/dev/sdb1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x1
Array UUID : 0b44a3b8:83eafabc:644afc87:bdb5b1f3
Name : servidor:0
   Creation Time : Sat Aug 5 23:10:50 2017
   Raid Level : raid5
   Raid Devices : 4

Avail Dev Size : 1953259520 (931.39 GiB 1000.07 GB) Array Size : 2929889280 (2794.16 GiB 3000.21 GB) Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262056 sectors, after=0 sectors State : clean
Device UUID : ddc94c8e:aab339df:2233112a:5c938bab

Internal Bitmap : 8 sectors from superblock Update Time : Tue Sep 19 01:36:51 2017
Bad Block Log : 512 entries available at offset 72 sectors Checksum : 626e25ae - correct
Events : 3106

Layout : left-symmetric
Chunk Size : 512K

Device Role : Active device 0
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

root@grafico:/# mdadm --examine /dev/sdc1
/dev/sdc1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 0b44a3b8:83eafabc:644afc87:bdb5b1f3
           Name : servidor:0
  Creation Time : Sat Aug 5 23:10:50 2017
     Raid Level : raid5
   Raid Devices : 4

Avail Dev Size : 1953259520 (931.39 GiB 1000.07 GB)
Array Size : 2929889280 (2794.16 GiB 3000.21 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262056 sectors, after=0 sectors
State : clean
Device UUID : 32271db0:38a5220c:c19968af:8fe1a3fb

Internal Bitmap : 8 sectors from superblock

    Update Time : Tue Sep 19 01:36:51 2017

Bad Block Log : 512 entries available at offset 72 sectors
Checksum : 86971d3c - correct
Events : 3106

Layout : left-symmetric
Chunk Size : 512K

Device Role : Active device 1
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

root@grafico:/# mdadm --examine /dev/sdd1
/dev/sdd1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 0b44a3b8:83eafabc:644afc87:bdb5b1f3
           Name : servidor:0
  Creation Time : Sat Aug 5 23:10:50 2017
     Raid Level : raid5
   Raid Devices : 4

Avail Dev Size : 1953259520 (931.39 GiB 1000.07 GB)
Array Size : 2929889280 (2794.16 GiB 3000.21 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262056 sectors, after=0 sectors
State : clean
Device UUID : 9014cf8b:ea7e22e2:9274be9d:9aeee689

Internal Bitmap : 8 sectors from superblock

    Update Time : Tue Sep 19 01:36:51 2017

Bad Block Log : 512 entries available at offset 72 sectors
Checksum : b4e1cc29 - correct
Events : 3106

Layout : left-symmetric
Chunk Size : 512K

Device Role : Active device 2
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

root@grafico:/# mdadm --examine /dev/sde1
/dev/sde1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x9
     Array UUID : 0b44a3b8:83eafabc:644afc87:bdb5b1f3
           Name : servidor:0
  Creation Time : Sat Aug 5 23:10:50 2017
     Raid Level : raid5
   Raid Devices : 4

Avail Dev Size : 1953259520 (931.39 GiB 1000.07 GB)
Array Size : 2929889280 (2794.16 GiB 3000.21 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
Unused Space : before=262056 sectors, after=0 sectors
State : clean
Device UUID : f95affb4:138bca63:d10df091:1f20af37

Internal Bitmap : 8 sectors from superblock

    Update Time : Tue Sep 19 01:36:51 2017

Bad Block Log : 512 entries available at offset 72 sectors - bad
blocks present.
Checksum : 1b3e988 - correct
Events : 3106

Layout : left-symmetric
Chunk Size : 512K

Device Role : Active device 3
Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

root@grafico:/# mdadm --detail /dev/md0
/dev/md0:
        Version : 1.2
  Creation Time : Sat Aug 5 23:10:50 2017
     Raid Level : raid5
     Array Size : 2929889280 (2794.16 GiB 3000.21 GB)
  Used Dev Size : 976629760 (931.39 GiB 1000.07 GB)
   Raid Devices : 4
  Total Devices : 4
    Persistence : Superblock is persistent

Intent Bitmap : Internal

Update Time : Tue Sep 19 01:36:51 2017
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 512K

Name : servidor:0
UUID : 0b44a3b8:83eafabc:644afc87:bdb5b1f3
Events : 3106

Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 33 1 active sync /dev/sdc1
2 8 49 2 active sync /dev/sdd1
3 8 65 3 active sync /dev/sde1

root@grafico:/# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid1] [raid10]
md0 : active (auto-read-only) raid5 sdb1[0] sde1[3] sdc1[1] sdd1[2]
      2929889280 blocks super 1.2 level 5, 512k chunk, algorithm 2 
[4/4] [UUUU]
      bitmap: 0/8 pages [0KB], 65536KB chunk

Joseba Ibarra

#1 lore raw
Quoted 5 lines · Joseba Ibarra

Hi.I have a RAID5 using 4 drives in a HO Proliant G8 Microserver

I got a Proxmox installed and the disks for RAID are associated with a specific VM with Debian 9. It worked like a charm.

Quoted 7 lines

But, some days ago i broke a proccess giving some permissions (sudo chmod....) to some folders into of the mounted /dev/md0. Then after restart the VM the RAID din't mount again. The raid contents very important data for me, so i'm not very sure what to do in order don't lose the data. So, i´m getting bit panic.

I need some guide to rebuild the system without losing the content.

Thanks for providing lots of useful data.

Quoted 8 lines
root@grafico:/# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4] [linear] [multipath] [raid0] 
[raid1] [raid10]
md0 : active (auto-read-only) raid5 sdb1[0] sde1[3] sdc1[1] sdd1[2]
       2929889280 blocks super 1.2 level 5, 512k chunk, algorithm 2 
[4/4] [UUUU]
       bitmap: 0/8 pages [0KB], 65536KB chunk

It appears that md0 has been successfully assembled. What does it contain? What do you expect it to contain? ext4? xfs? btrfs? LVM volume ??

What does "pvscan" show?
What does "fsck -n /dev/md0" show?
What happens when you "mount /dev/md0 /mnt" ?

NeilBrown