How to mount single active disk from a failed Raid1

vulcan4d · 25. September 2014

Hey guys one of my Raid1 1GB disks failed and I lost the ability to access the files on the working drive. I don't plan to replace the broken disk because I plan to move the files from the working drive to my Raid5 setup. I simply cannot access the files in this "clean,degraded" state. I looked up the folders under /media/ but nothing. My SMB won't access it either. I figured I'll remove the Raid under Raid management and mount the disk as a single drive. Since the 2 disks were mirrored it should have all the files. Problem now is neither under "File system" nor "Raid management" does the drive show up. How do I get omv to see the drive again? Under filesystem it only shows "missing" besides my Raid5 array.

Edit: Updated outputs posted in reply

subzero79 · 25. September 2014

Can you output the results of blkid and also a cat /etc/mdadm/mdadm.conf
Your raid1 array was it composed of sdd and sde?
With the info you provided from /proc/mdadm I can't even see the degraded array. Even with [1/2] degraded array you should see it and be able to mount it.

vulcan4d · 25. September 2014

Thank you for the help subzero. I'll give you fresh outputs including the ones you requested because after a restart my drives reshuffled for some reason. My raid arrays are simply named Raid1 (failed) and Raid3
Raid1 consists of: sda & sde with the output below

The GUI shows:
Physical disks: both drives present for Raid1
Raid Management: Raid1 is not here and when I pick create, there are no disks to choose
File system: N/A missing

blkid

Code

/dev/sdb: UUID="67b71032-b48c-50a6-dc81-7b2eefd4e939" UUID_SUB="2a18be27-9a95-6828-83c2-5ee01a1539bc" LABEL="nas2:raid3" TYPE="linux_raid_member"
/dev/md0: LABEL="RaidArray3" UUID="84808b75-2b74-405f-b7e2-77c33f918a04" TYPE="ext4"
/dev/sdc: UUID="67b71032-b48c-50a6-dc81-7b2eefd4e939" UUID_SUB="75c609cb-c646-324f-0f73-e30630d14260" LABEL="nas2:raid3" TYPE="linux_raid_member"
/dev/sdf1: UUID="275e2463-bb97-472c-a0e8-6962e0538355" TYPE="ext4"
/dev/sdf5: UUID="e45fde5b-7be1-45cf-a124-02e16fda8d82" TYPE="swap"
/dev/sda: UUID="bc267fc1-4a05-c856-c378-2278946ff688" UUID_SUB="e979f3a4-81a0-ca08-e124-066261c6d3ff" LABEL="nas2:raid1" TYPE="linux_raid_member"
/dev/sdd: UUID="67b71032-b48c-50a6-dc81-7b2eefd4e939" UUID_SUB="6a783c49-41b1-00c1-9287-d6b9f8e05019" LABEL="nas2:raid3" TYPE="linux_raid_member"

cat /etc/mdadm/mdadm.conf

Code

# mdadm.conf
#
# Please refer to mdadm.conf(5) for information about this file.
#


# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
# Note, if no DEVICE line is present, then "DEVICE partitions" is assumed.
# To avoid the auto-assembly of RAID devices a pattern that CAN'T match is
# used if no RAID devices are configured.
DEVICE partitions


# auto-create devices with Debian standard permissions
CREATE owner=root group=disk mode=0660 auto=yes


# automatically tag new arrays as belonging to the local system
HOMEHOST <system>


# definitions of existing MD arrays
ARRAY /dev/md0 metadata=1.2 name=nas2:raid3 UUID=67b71032:b48c50a6:dc817b2e:efd4e939

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cat /proc/mdstat

Code

Personalities : [raid6] [raid5] [raid4]
md0 : active raid5 sdb[0] sdd[3] sdc[1]
      5860530176 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]


unused devices: <none>

fdisk -l

Code

Disk /dev/sda: 1000.2 GB, 1000203804160 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953523055 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
Disk identifier: 0x00000000


Disk /dev/sda doesn't contain a valid partition table


Disk /dev/sdb: 3000.6 GB, 3000592982016 bytes
255 heads, 63 sectors/track, 364801 cylinders, total 5860533168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/sdb doesn't contain a valid partition table


Disk /dev/sdc: 3000.6 GB, 3000592982016 bytes
255 heads, 63 sectors/track, 364801 cylinders, total 5860533168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/sdc doesn't contain a valid partition table


Disk /dev/sdd: 3000.6 GB, 3000592982016 bytes
255 heads, 63 sectors/track, 364801 cylinders, total 5860533168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x00000000


Disk /dev/sdd doesn't contain a valid partition table


Disk /dev/sde: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 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
Disk identifier: 0x00000000


Disk /dev/sde doesn't contain a valid partition table


Disk /dev/sdf: 60.0 GB, 60011642880 bytes
255 heads, 63 sectors/track, 7296 cylinders, total 117210240 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
Disk identifier: 0x8be41c7d


   Device Boot      Start         End      Blocks   Id  System
/dev/sdf1   *        2048    37380095    18689024   83  Linux
/dev/sdf2        37380096   117210239    39915072    5  Extended
/dev/sdf5        37382144   117209087    39913472   82  Linux swap / Solaris


Disk /dev/md0: 6001.2 GB, 6001182900224 bytes
2 heads, 4 sectors/track, 1465132544 cylinders, total 11721060352 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 524288 bytes / 1048576 bytes
Disk identifier: 0x00000000


Disk /dev/md0 doesn't contain a valid partition table

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cat /etc/fstab

Code

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
proc            /proc           proc    defaults        0       0
# / was on /dev/sda1 during installation
UUID=275e2463-bb97-472c-a0e8-6962e0538355 /               ext4    errors=remount-ro 0       1
# swap was on /dev/sda5 during installation
UUID=e45fde5b-7be1-45cf-a124-02e16fda8d82 none            swap    sw              0       0
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0
tmpfs           /tmp            tmpfs   defaults        0       0
# >>> [openmediavault]
UUID=84808b75-2b74-405f-b7e2-77c33f918a04 /media/84808b75-2b74-405f-b7e2-77c33f918a04 ext4 defaults,nofail,acl,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0 0 2
UUID=9618ef3a-743a-4fd9-be3d-fd4843868a37 /media/9618ef3a-743a-4fd9-be3d-fd4843868a37 ext4 defaults,nofail,acl,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0 0 2
UUID=0b0e0388-79e1-463d-8b09-a0a084babe12 /media/0b0e0388-79e1-463d-8b09-a0a084babe12 ext4 defaults,nofail,acl,user_xattr,noexec,usrjquota=aquota.user,grpjquota=aquota.group,jqfmt=vfsv0 0 2
# <<< [openmediavault]

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subzero79 · 25. September 2014

Just to confirm....you raid1 array (name) is actually a RAID1 array? i mean mirror?

The OMV UI doesn't allow building a degraded array. However you can use the mdadm tools re-build your raid1 as degraded array.
You can construct a mirror with one disk missing (sda available and sde missing), after that OMV should be able to see it and mount the array, from there you can move your files to md0.

I am pretty sure I saw sde in your initial post, did you pull it off?

vulcan4d · 26. September 2014

You are correct, dumb naming but it works :). Raid1 mirror was 1TB and consisted of SDA 1TB drive & SDE 1.5TB drive. It wasn't sde initially, that is why I pulled it off after realizing it changed. Didn't want to confuse anyone with the updated information.

That is good advice, didn't know the UI couldn't help me if a drive failed for a mirror raid. I'll go ahead and read about using the mdadm tools since I am unfamiliar. I'll report back shortly. Thank you.

vulcan4d · 26. September 2014

wow it worked. I read up on what you said and creating a degraded Raid1 array and I stubled upon this article:

Zitat

https://www.suse.com/documenta…ta/raidmdadmdegraded.html

For future reference anyone who has this problem again can simply re-create the raid array. I was worried this would overwrite as the command said there was already an existing one but poof it worked

Zitat

mdadm --create /dev/md1 -l 1 -n 2 /dev/sda missing

md1 - is the name of the new array. I already had md0
sda - is the single drive I needed to access

Thank you for the great help!

subzero79 · 26. September 2014

Also take a look at the backup plugin for offline system operations on HD and raid arrays. As for training in mdadm operations I would recommend the virtual appliance for omv in virtualbox. Comes ready with 9 disks to play around, create, destroy, rebuild etc, whatever you feel like.

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