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I have ubuntu 18.04.2 based server with Software based RAID5 partition for Data. After rebooting the system. It is unable to mount automatically. When I try to mount using command "sudo mount -a". I get following error.

mount: wrong fs type, bad option, bad superblock on /dev/md0,
       missing codepage or helper program, or other error

       In some cases useful info is found in syslog - try
       dmesg | tail or so.

dmesg | tail command out is as following

[   45.596679] Bridge firewalling registered
[   45.628950] nf_conntrack version 0.5.0 (65536 buckets, 262144 max)
[   45.712031] ip_tables: (C) 2000-2006 Netfilter Core Team
[   45.765630] Initializing XFRM netlink socket
[   45.772559] Netfilter messages via NETLINK v0.30.
[   45.774814] ctnetlink v0.93: registering with nfnetlink.
[   45.944103] IPv6: ADDRCONF(NETDEV_UP): docker0: link is not ready
[   46.792337] aufs au_opts_verify:1597:dockerd[2191]: dirperm1 breaks the protection by the permission bits on the lower branch
[   75.420002] EXT4-fs (md0): can't read group descriptor 5242
[  605.733833] EXT4-fs (md0): can't read group descriptor 5242

Output of mdadm --detail /dev/md0 is as following

dev/md0:
        Version : 1.2
  Creation Time : Sun Jan  6 20:39:33 2002
     Raid Level : raid5
     Array Size : 46883119104 (44711.23 GiB 48008.31 GB)
  Used Dev Size : 5860389888 (5588.90 GiB 6001.04 GB)
   Raid Devices : 9
  Total Devices : 8
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Fri Jun  7 09:19:58 2019
          State : clean, degraded 
 Active Devices : 8
Working Devices : 8
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : ubuntu:0  (local to host ubuntu)
           UUID : e5109f94:e146b6d5:686e76d7:36787295
         Events : 869392

    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
       8       0        0        8      removed
       5       8      113        5      active sync   /dev/sdh1
       6       8      129        6      active sync   /dev/sdi1
       7       8      145        7      active sync   /dev/sdj1
       8       8      161        8      active sync   /dev/sdk1

Output for fsck /dev/md0

fsck from util-linux 2.27.1
e2fsck 1.42.13 (17-May-2015)
fsck.ext4: Attempt to read block from filesystem resulted in short read while trying to open /dev/md0
Could this be a zero-length partition?

Output for mke2fs -n /dev/sdg1

mke2fs 1.42.13 (17-May-2015)
/dev/sdg1 contains a linux_raid_member file system labelled 'ubuntu:0'
Proceed anyway? (y,n) y
Creating filesystem with 1465130240 4k blocks and 183144448 inodes
Filesystem UUID: f2f50279-73b6-4d89-9251-e5056ace74de
Superblock backups stored on blocks: 
    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 
    4096000, 7962624, 11239424, 20480000, 23887872, 71663616, 78675968, 
    102400000, 214990848, 512000000, 550731776, 644972544

Please help.

Thank you

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  • Have you tried # fsck /dev/md0?
    – RonJohn
    Jun 7, 2019 at 18:02
  • Yes I did. I have updated the query.
    – Manu
    Jun 7, 2019 at 19:35
  • That looks bad. Do you have a recent backup? I found this which might help: unix.stackexchange.com/questions/114429/…
    – RonJohn
    Jun 7, 2019 at 19:51
  • NO, we didn't :'( . The raid is ~50TB. It will not be possible to create mirror for 50TB file system.
    – Manu
    Jun 7, 2019 at 20:12
  • I am thinking to follow instruction on serverfault.com/questions/206511/… . However, I am worried about loosing data as well.
    – Manu
    Jun 7, 2019 at 21:09

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