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mdadm raid10 assemble fail

Hi all,

I have tried to google this one but I can't seem to find an answer.
I have a raid10 with a failed drive and one that seems a bit out of date but with a similar number of events to the 2 good ones. I would like to reassemble it (even RO) to backup the data but nothing works. I have tried

Code:

sudo mdadm --assemble --run -o -vv --force /dev/md127 /dev/sdd1 /dev/sdf1 /dev/sdc1

and I get:

Code:

mdadm: looking for devices for /dev/md127

mdadm: UUID differs from /dev/md/0.

mdadm: UUID differs from /dev/md/0.

mdadm: UUID differs from /dev/md/0.

mdadm: /dev/sdd1 is identified as a member of /dev/md127, slot 1.

mdadm: /dev/sdf1 is identified as a member of /dev/md127, slot 3.

mdadm: /dev/sdc1 is identified as a member of /dev/md127, slot 0.

mdadm: added /dev/sdd1 to /dev/md127 as 1

mdadm: no uptodate device for slot 4 of /dev/md127

mdadm: added /dev/sdf1 to /dev/md127 as 3 (possibly out of date)

mdadm: added /dev/sdc1 to /dev/md127 as 0

mdadm: failed to RUN_ARRAY /dev/md127: Input/output error

mdadm: Not enough devices to start the array.

Here is the output of

Code:

sudo mdadm --examine /dev/sd[c-f]1

Code:

/dev/sdc1:

          Magic : a92b4efc

        Version : 1.2

    Feature Map : 0x0

    Array UUID : e1f1e05e:4d88b3ba:605c5318:3305a6c2

          Name : raidVolume1:5

  Creation Time : Fri Jan 13 14:04:24 2012

    Raid Level : raid10

  Raid Devices : 4



 Avail Dev Size : 2930273072 (1397.26 GiB 1500.30 GB)

    Array Size : 2930272256 (2794.53 GiB 3000.60 GB)

  Used Dev Size : 2930272256 (1397.26 GiB 1500.30 GB)

    Data Offset : 2048 sectors

  Super Offset : 8 sectors

  Unused Space : before=1960 sectors, after=816 sectors

          State : active

    Device UUID : 77bc4c0d:bf06805a:80c949d6:5f297478



    Update Time : Sun Jul  2 00:57:01 2017

  Bad Block Log : 512 entries available at offset 72 sectors

      Checksum : 61ef5bf1 - correct

        Events : 5297



        Layout : near=2

    Chunk Size : 512K



  Device Role : Active device 0

  Array State : AA.A ('A' == active, '.' == missing, 'R' == replacing)

/dev/sdd1:

          Magic : a92b4efc

        Version : 1.2

    Feature Map : 0x0

    Array UUID : e1f1e05e:4d88b3ba:605c5318:3305a6c2

          Name : raidVolume1:5

  Creation Time : Fri Jan 13 14:04:24 2012

    Raid Level : raid10

  Raid Devices : 4



 Avail Dev Size : 2930273072 (1397.26 GiB 1500.30 GB)

    Array Size : 2930272256 (2794.53 GiB 3000.60 GB)

  Used Dev Size : 2930272256 (1397.26 GiB 1500.30 GB)

    Data Offset : 2048 sectors

  Super Offset : 8 sectors

  Unused Space : before=1960 sectors, after=816 sectors

          State : active

    Device UUID : 05f19f85:63972191:d43f66c0:3e3df7bd



    Update Time : Sun Jul  2 00:57:01 2017

  Bad Block Log : 512 entries available at offset 72 sectors

      Checksum : 4083ab58 - correct

        Events : 5297



        Layout : near=2

    Chunk Size : 512K



  Device Role : Active device 1

  Array State : AA.A ('A' == active, '.' == missing, 'R' == replacing)

/dev/sde1:

          Magic : a92b4efc

        Version : 1.2

    Feature Map : 0x0

    Array UUID : e1f1e05e:4d88b3ba:605c5318:3305a6c2

          Name : raidVolume1:5

  Creation Time : Fri Jan 13 14:04:24 2012

    Raid Level : raid10

  Raid Devices : 4



 Avail Dev Size : 2930273072 (1397.26 GiB 1500.30 GB)

    Array Size : 2930272256 (2794.53 GiB 3000.60 GB)

  Used Dev Size : 2930272256 (1397.26 GiB 1500.30 GB)

    Data Offset : 2048 sectors

  Super Offset : 8 sectors

  Unused Space : before=1960 sectors, after=816 sectors

          State : active

    Device UUID : f15b1bd0:0f36825f:f7eaeb59:06a8f229



    Update Time : Sun Feb  5 02:00:08 2017

  Bad Block Log : 512 entries available at offset 72 sectors

      Checksum : 5e2785f2 - correct

        Events : 4833



        Layout : near=2

    Chunk Size : 512K



  Device Role : Active device 2

  Array State : AAAA ('A' == active, '.' == missing, 'R' == replacing)

/dev/sdf1:

          Magic : a92b4efc

        Version : 1.2

    Feature Map : 0x0

    Array UUID : e1f1e05e:4d88b3ba:605c5318:3305a6c2

          Name : raidVolume1:5

  Creation Time : Fri Jan 13 14:04:24 2012

    Raid Level : raid10

  Raid Devices : 4



 Avail Dev Size : 2930273072 (1397.26 GiB 1500.30 GB)

    Array Size : 2930272256 (2794.53 GiB 3000.60 GB)

  Used Dev Size : 2930272256 (1397.26 GiB 1500.30 GB)

    Data Offset : 2048 sectors

  Super Offset : 8 sectors

  Unused Space : before=1968 sectors, after=816 sectors

          State : active

    Device UUID : 06d4dd09:d3e37bea:56c43770:2f4df042



    Update Time : Sun May  7 00:57:03 2017

      Checksum : 52949aef - correct

        Events : 5293



        Layout : near=2

    Chunk Size : 512K



  Device Role : Active device 3

  Array State : AA.A ('A' == active, '.' == missing, 'R' == replacing)

The only option seems to recreate the array but since this is risky, I'd like to see if there's a safer option first.
Any help would be greatly appreciated.

Gnewbee

It seems you did not fail out the failed HD first and then remove it from the array before stopping the array. So now you are trying to start the array without all the drives and it cannot start that way as evident by your output;

Code:

mdadm: Not enough devices to start the array.

You might try starting your array with all 4 disks and then fail out /dev/sde1 from the array like this;

Code:

mdadm --manage /dev/md127 --fail /dev/sde1

mdadm --manage /dev/md127 --remove /dev/sde1

Once you have a new drive you can added it like this;

Code:

mdadm --manage /dev/md127 --add /dev/sde1

Hi

The problem is I can't start it with any number of drives. I have also tried 4 drives

Code:

sudo mdadm --assemble --run -o -vv --force /dev/md5 /dev/sd[c-f]1

but I get:

Code:

mdadm: looking for devices for /dev/md5

mdadm: UUID differs from /dev/md/0.

mdadm: UUID differs from /dev/md/0.

mdadm: UUID differs from /dev/md/0.

mdadm: UUID differs from /dev/md/0.

mdadm: /dev/sdc1 is identified as a member of /dev/md5, slot 0.

mdadm: /dev/sdd1 is identified as a member of /dev/md5, slot 1.

mdadm: /dev/sde1 is identified as a member of /dev/md5, slot 2.

mdadm: /dev/sdf1 is identified as a member of /dev/md5, slot 3.

mdadm: added /dev/sdd1 to /dev/md5 as 1

mdadm: added /dev/sde1 to /dev/md5 as 2 (possibly out of date)

mdadm: added /dev/sdf1 to /dev/md5 as 3 (possibly out of date)

mdadm: added /dev/sdc1 to /dev/md5 as 0

mdadm: failed to RUN_ARRAY /dev/md5: Input/output error

mdadm: Not enough devices to start the array.

I suspect the problem is the possibly out of date comment but I already tried the force option.

Thanks in advance for any help

Gnewbee

Wait your first post you were using md127 and now you are trying to use md5?

What does your mdadm.conf file have in it?

Well spotted. The 127 was what it was trying to auto-assign so I reused it before looking at my mdadm.conf file and seeing the 5.
Here's the content of the file:

Code:

# mdadm.conf

#

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

#



# by default (built-in), scan all partitions (/proc/partitions) and all

# containers for MD superblocks. alternatively, specify devices to scan, using

# wildcards if desired.

#DEVICE partitions containers



# 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>



# instruct the monitoring daemon where to send mail alerts

MAILADDR root



# definitions of existing MD arrays

ARRAY /dev/md/0  metadata=1.2 UUID=2f536e6c:128e0beb:22021404:36cc8865 name=ubuntu:0

#ARRAY /dev/md/5  metadata=1.2 UUID=e1f1e05e:4d88b3ba:605c5318:3305a6c2 name=raidVolume1:5



# This file was auto-generated on Wed, 11 Jan 2017 12:49:28 +0000

# by mkconf $Id$

You should also take notice that your array is /dev/md/0 not /dev/md5 according to this file.

Actually md0 is a raid1 volume for my root, home, ... which is still working fortunately
md5 is just data (which I'd still like to recover)

OK, so why is it commented out then?

Have you tried:

Code:

mdadm --assemble --scan --force

md0 is there, md5 is commented out but I can't really remember why. It may be the ID changed and wouldn't mount like that so I commented. Truth is I really don't remember.

Is there no risk to mounted and healthy volumes (the root md0 in my case) to running:

Code:

mdadm --assemble --scan --force

Thanks

Gnewbee