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mimaste7

Member

Registered: 2015-03-29

Posts: 2

mount: unknown filesystem type 'linux_raid_member'

I am trying to recover data from partitions on a RAID 1 array. 

However, when I try to mount either of the partitions (/dev/sdc1 or /dev/sdc2), I get the error "mount: unknown filesystem type 'linux_raid_member'". 
the mount command I used was (I did the same for sdc2):

mount /dev/sdc1 /mnt/backup

I also ran 'sudo smart ctl' and got "SMART Health Status: OK" for both partitions.  So I think I can rule out disk health issues.

I tried 'mdadm --assemble --scan' and got:

mdadm: failed to add /dev/sdc1 to /dev/md/1: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md/1: Invalid argument
mdadm: failed to add /dev/sdc2 to /dev/md/2: Invalid argument
mdadm: failed to RUN_ARRAY /dev/md/2: Invalid argument

This is the output of 'sudo fdisk -l /dev/sdc':

Disk /dev/sdc: 3.7 TiB, 4000787030016 bytes, 7814037168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 0A7D7BB3-7070-2141-83F2-69FDC85C9E69

Device        Start      End Sectors  Size Type
/dev/sdc1   2000896 11990919 9990024  4.8G Linux RAID
/dev/sdc2  12000002 13998857 1998856  976M Linux RAID

the output of 'sudo mdadm --examine /dev/sdc1':

/dev/sdc1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 3d41c60c:405653fd:39c88afe:9fe03176
           Name : LS421DE-EM4F5:1
  Creation Time : Wed Oct 31 01:03:49 2007
     Raid Level : raid1
   Raid Devices : 2

Avail Dev Size : 9990144 (4.76 GiB 5.11 GB)
     Array Size : 4995008 (4.76 GiB 5.11 GB)
  Used Dev Size : 9990016 (4.76 GiB 5.11 GB)
    Data Offset : 8192 sectors
   Super Offset : 8 sectors
   Unused Space : before=8112 sectors, after=18446744073709543432 sectors
          State : clean
    Device UUID : e2450711:ceb78514:cad2b878:87dabe05

    Update Time : Tue Mar 24 18:34:56 2015
       Checksum : f1310b3 - correct
         Events : 239666

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

and the output of 'sudo mdadm --examine /dev/sdc2':

/dev/sdc2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : b2c77f77:9d9ae7ac:313e5f4a:a378df2a
           Name : LS421DE-EM4F5:2
  Creation Time : Wed Oct 31 01:03:49 2007
     Raid Level : raid1
   Raid Devices : 2

Avail Dev Size : 1998975 (976.23 MiB 1023.48 MB)
     Array Size : 999424 (976.16 MiB 1023.41 MB)
  Used Dev Size : 1998848 (976.16 MiB 1023.41 MB)
    Data Offset : 1024 sectors
   Super Offset : 8 sectors
   Unused Space : before=944 sectors, after=18446744073709550600 sectors
          State : clean
    Device UUID : fd4ca8dc:5994b788:4d6537ff:d4dbe0a9

    Update Time : Tue Mar 24 18:10:31 2015
       Checksum : 935fba7c - correct
         Events : 624

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

Please help me.  Anything is appreciated.  Thanks in advance.

EDIT: To be sure, I should have more data on the disk than what is shown in the partitions.  I've already ran 'testdisk' on this disk.

Last edited by mimaste7 (2015-03-29 05:24:56)

frostschutz

Member

Registered: 2013-11-15

Posts: 1,456

Re: mount: unknown filesystem type 'linux_raid_member'

However, when I try to mount either of the partitions (/dev/sdc1 or /dev/sdc2), I get the error "mount: unknown filesystem type 'linux_raid_member'".

This message simply means that the device is member of a RAID. You are supposed to start the RAID and then mount the RAID, not mount the underlying device.

If for some reason the RAID can not be started (check /proc/mdstat as well, you might have to --stop before you --assemble --scan), then you can circumvent this by using a loop mount

mount -o ro,loop,offset=$((8192*512)) /dev/sdc1 /mnt/sdc1

The offset in question is what's shown in the mdadm --examine output as "Data Offset".

Of course this requires a filesystem to be on the RAID; if it's something else, like LVM or LUKS, you have to go through losetup and then enable the other layers individually.

I'm not sure what to do about wrong partition sizes; you might need TestDisk to check if other partitions can be found.

Last edited by frostschutz (2015-03-29 14:02:43)

mimaste7

Member

Registered: 2015-03-29

Posts: 2

Re: mount: unknown filesystem type 'linux_raid_member'

Thanks for the reply!!
I have already ran testdisk.  It attempted to restore the partitions, but I'm not 100% sure how effective it was. 

In any case, I tried 'sudo mount -o ro,loop,offset=$((8192*512)) /dev/sdb1 /mnt/backup/' and I got the following error

mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error

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

I also ran 'sudo mount -o ro,loop,offset=$((1024*512)) /dev/sdb2 /mnt/backup/' and got this error:

mount: unknown filesystem type 'swap'

Which seems odd because I don't remember ever setting up a swap space on this disk.

Here's the output from 'dmesg | tail -25':

[ 4356.952269] scsi host6: usb-storage 7-1:1.0
[ 4357.955511] scsi 6:0:0:0: Direct-Access     ST4000DM 000-1F2168       CC52 PQ: 0 ANSI: 5
[ 4357.956939] sd 6:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16).
[ 4357.957263] sd 6:0:0:0: [sdb] 7814037168 512-byte logical blocks: (4.00 TB/3.63 TiB)
[ 4357.959435] sd 6:0:0:0: [sdb] Write Protect is off
[ 4357.959451] sd 6:0:0:0: [sdb] Mode Sense: 28 00 00 00
[ 4357.962322] sd 6:0:0:0: [sdb] No Caching mode page found
[ 4357.962335] sd 6:0:0:0: [sdb] Assuming drive cache: write through
[ 4357.963301] sd 6:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16).
[ 4358.000908]  sdb: sdb1 sdb2
[ 4358.002117] sd 6:0:0:0: [sdb] Very big device. Trying to use READ CAPACITY(16).
[ 4358.003882] sd 6:0:0:0: [sdb] Attached SCSI disk
[ 4358.084885] md: sdb1 does not have a valid v1.2 superblock, not importing!
[ 4358.084904] md: md_import_device returned -22
[ 4358.084975] md: md1 stopped.
[ 4358.108807] md: sdb2 does not have a valid v1.2 superblock, not importing!
[ 4358.108878] md: md_import_device returned -22
[ 4358.108998] md: md2 stopped.
[ 4538.771028] EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem
[ 4538.771275] EXT4-fs (loop0): bad geometry: block count 1248752 exceeds size of device (1247729 blocks)

Output from 'cat /proc/mdstat'

Personalities :
unused devices: <none>

To my knowledge, this is not a LVM/LUKS setup.  I bought a Buffalo NAS and it used the default RAID configuration (the Buffalo support guy (higher than Level 1 support, for what its worth) told me the default is RAID 1, which makes sense since that's what 'mdadm --examine' says). 

I apologize for my lack of knowledge about all this.  I'm fresh meat to NAS/RAID/etc.

frostschutz

Member

Registered: 2013-11-15

Posts: 1,456

Re: mount: unknown filesystem type 'linux_raid_member'

[ 4538.771028] EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem
[ 4538.771275] EXT4-fs (loop0): bad geometry: block count 1248752 exceeds size of device (1247729 blocks)

Well, that just means the partition is a little too small.

If you add the partition offset as well you can use /dev/sdx instead of /dev/sdx1, that gives you a loop device limited only by the disk size.