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#1 2015-01-21 13:03:42

colmi
Member
Registered: 2015-01-21
Posts: 3

[raid] A mdadm array is not accessible after update

Hi everyone,

Last week I updated one of my computers, which has not been updated for a year or so (it was offline too).
Since the update and reboot, I can't seem to access a mdadm array which was used for storage.

My kernel is the stock archlinux one:

[13:35][root@plop][~]# uname -a
Linux plop 3.17.6-1-ARCH #1 SMP PREEMPT Sun Dec 7 23:43:32 UTC 2014 x86_64 GNU/Linux

The md and raid modules seem to be correcly loaded:

[13:41][root@plop][~]# lsmod | grep -i '\(md\|raid\)'
raid456                81478  0 
async_raid6_recov      16582  1 raid456
async_memcpy           12350  2 raid456,async_raid6_recov
async_pq               12476  2 raid456,async_raid6_recov
async_xor              12385  3 async_pq,raid456,async_raid6_recov
async_tx               12566  5 async_pq,raid456,async_xor,async_memcpy,async_raid6_recov
raid6_pq               99334  2 async_pq,async_raid6_recov
raid1                  34552  0 
md_mod                115864  2 raid456,raid1
kvm_amd                59131  0 
kvm                   421519  1 kvm_amd
edac_mce_amd           21166  0

The array is found in the disk superblocks (it is located on the whole sdb sdc and sdd drives):

[13:41][root@salon][~]# mdadm -E --scan
ARRAY /dev/md/666  metadata=1.2 UUID=d917d21c:be76bfcc:b8261743:82dd8cd0 name=plop:666

My /etc/mdadm.conf file is:

[13:48][root@plop][~]# cat /etc/mdadm.conf | grep -v '#'
DEVICE /dev/sdb /dev/sdc /dev/sdd
ARRAY /dev/md/666  metadata=1.2 UUID=d917d21c:be76bfcc:b8261743:82dd8cd0 name=plop:666

However my device is inaccessible in /dev. There is no /dev/md* file or directory whatsoever.
The array is not mentionned in /proc/mdstat:

[13:54][root@plop][~]# cat /proc/mdstat 
Personalities : [raid6] [raid5] [raid4] 
unused devices: <none>

And when I try to force assemble it:

[13:58][root@plop][~]# mdadm -A --scan
mdadm: unexpected failure opening /dev/md666
[13:57][root@plop][~]# mdadm -A /dev/md/666
mdadm: unexpected failure opening /dev/md666

Any idea anyone ?

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#2 2015-01-21 15:03:07

alphaniner
Member
From: Ancapistan
Registered: 2010-07-12
Posts: 2,810

Re: [raid] A mdadm array is not accessible after update

Maybe the output of mdadm -E /dev/sd[bcd] would be informative.

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner

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#3 2015-01-21 16:05:44

jasonwryan
Anarchist
From: .nz
Registered: 2009-05-09
Posts: 30,424
Website

Re: [raid] A mdadm array is not accessible after update

Why are you posting the output from two (apparently) different hosts?

Arch + dwm   •   Mercurial repos  •   Surfraw

Registered Linux User #482438

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#4 2015-01-21 23:40:29

colmi
Member
Registered: 2015-01-21
Posts: 3

Re: [raid] A mdadm array is not accessible after update

@alphaniner: here is the full information for the disks

[00:33][root@plop][~]# mdadm -E /dev/sd[bcd]
/dev/sdb
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : d917d21c:be76bfcc:b8261743:82dd8cd0
           Name : plop:666  (local to host plop)
  Creation Time : Sat Dec 15 10:37:16 2012
     Raid Level : raid5
   Raid Devices : 3

 Avail Dev Size : 5860271024 (2794.40 GiB 3000.46 GB)
     Array Size : 5860270080 (5588.79 GiB 6000.92 GB)
  Used Dev Size : 5860270080 (2794.39 GiB 3000.46 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262064 sectors, after=944 sectors
          State : clean
    Device UUID : e84c1b10:8c9d30c6:35b2f255:9de0581c

    Update Time : Fri Oct 10 00:26:50 2014
       Checksum : f402a6cd - correct
         Events : 70435

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 0
   Array State : AAA ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdc:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : d917d21c:be76bfcc:b8261743:82dd8cd0
           Name : plop:666  (local to host plop)
  Creation Time : Sat Dec 15 10:37:16 2012
     Raid Level : raid5
   Raid Devices : 3

 Avail Dev Size : 5860271024 (2794.40 GiB 3000.46 GB)
     Array Size : 5860270080 (5588.79 GiB 6000.92 GB)
  Used Dev Size : 5860270080 (2794.39 GiB 3000.46 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262064 sectors, after=944 sectors
          State : clean
    Device UUID : 7aa650b7:6689efb9:d37dbd39:38183779

    Update Time : Fri Oct 10 00:26:50 2014
       Checksum : cf9fef74 - correct
         Events : 70435

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 1
   Array State : AAA ('A' == active, '.' == missing, 'R' == replacing)
/dev/sdd:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : d917d21c:be76bfcc:b8261743:82dd8cd0
           Name : plop:666  (local to host plop)
  Creation Time : Sat Dec 15 10:37:16 2012
     Raid Level : raid5
   Raid Devices : 3

 Avail Dev Size : 5860271024 (2794.40 GiB 3000.46 GB)
     Array Size : 5860270080 (5588.79 GiB 6000.92 GB)
  Used Dev Size : 5860270080 (2794.39 GiB 3000.46 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262064 sectors, after=944 sectors
          State : clean
    Device UUID : 56f3c5bb:686073e2:d0677a15:7ee63488

    Update Time : Fri Oct 10 00:26:50 2014
       Checksum : e753cb97 - correct
         Events : 70435

         Layout : left-symmetric
     Chunk Size : 512K

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

@jasonwryan: my bad, it all comes from the same host, just that I ineffectively tried to camouflage the real hostname when posting... Epic fail is the term.

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#5 2015-01-27 10:28:43

pgoetz
Member
From: Austin, Texas
Registered: 2014-02-21
Posts: 355

Re: [raid] A mdadm array is not accessible after update

First, use blkid to make sure that the type of all the RAID member partitions is set to "linux_raid_member".

Next, did you try to assemble the RAID?

mdadm --assemble --scan -v

Finally, it sounds like your RAID superblock has become corrupted?  Try following the instructions here to rebuild your RAID superblock.

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#6 2015-02-03 20:12:42

colmi
Member
Registered: 2015-01-21
Posts: 3

Re: [raid] A mdadm array is not accessible after update

Hi,

Sorry for the lag. It was vacation time for me smile.
Here are the results you asked for.

[21:00][root@plop][~]# blkid
/dev/sdc: UUID="d917d21c-be76-bfcc-b826-174382dd8cd0" UUID_SUB="7aa650b7-6689-efb9-d37d-bd3938183779" LABEL="plop:666" TYPE="linux_raid_member"
/dev/sdb: UUID="d917d21c-be76-bfcc-b826-174382dd8cd0" UUID_SUB="e84c1b10-8c9d-30c6-35b2-f2559de0581c" LABEL="plop:666" TYPE="linux_raid_member"
/dev/sda1: UUID="4274e216-94f4-4830-8120-aa6451318e90" TYPE="ext2" PARTUUID="2d5509d2-01"
/dev/sda2: UUID="92339f46-71ba-41de-abe5-70740d7554c9" TYPE="ext4" PARTUUID="2d5509d2-02"
/dev/sda3: UUID="e568aecf-5059-4f9d-874f-53437c72b822" TYPE="ext4" PARTUUID="2d5509d2-03"
/dev/sda4: UUID="f8791d99-e21a-403a-81b6-255215e8df32" TYPE="swap" PARTUUID="2d5509d2-04"
/dev/sdd: UUID="d917d21c-be76-bfcc-b826-174382dd8cd0" UUID_SUB="56f3c5bb-6860-73e2-d067-7a157ee63488" LABEL="plop:666" TYPE="linux_raid_member"
[21:00][root@plop][~]# mdadm --assemble --scan -v
mdadm: looking for devices for /dev/md/666
mdadm: unexpected failure opening /dev/md666

It is not the first time such a thing happens to me. Last time, the course I took was to:
- assemble the array using a live cd (in that configuration the array was successfully assembled)
- remove a disk from it
- format that disk
- copy the data from the degraded arary
- reboot to the current system
- build a new array from the 2 disks of the old array
- copy the data to the new array
- wipe again the lone disk
- and then re-add it to the new array.
It worked, but it was cumbersome, and far too risky to my taste.

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#7 2015-02-04 15:07:56

alphaniner
Member
From: Ancapistan
Registered: 2010-07-12
Posts: 2,810

Re: [raid] A mdadm array is not accessible after update

I don't see anything in the 'mdadm -E /dev/sdX' output that indicates any problems, but I'm not an expert or anything. Maybe try some live cds from between the time it was working to present to get an idea of when (eg. kernel & mdadm version) it stopped working. You might also consider the linux-raid mailing list for more help.

But whether the Constitution really be one thing, or another, this much is certain - that it has either authorized such a government as we have had, or has been powerless to prevent it. In either case, it is unfit to exist.
-Lysander Spooner

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