mdadm, assembling array after interrupt during growing

[phosphide]

Hi,

I am trying to assemble a partially-grown RAID5 array (I interrupted the growing process on purpose, to ensure I can recover data if something interrupts growing the array on which I keep my real data).

The OS is Fedora 10. The array was created using anaconda, during the installation. It consisted of sda2, sdb2, sdc2. /boot is on /dev/sda1 and sd[bcd]1 don't matter.

[root@f10-raid ~]# cat /etc/mdadm.conf
# mdadm.conf written out by anaconda
DEVICE partitions
MAILADDR root

ARRAY /dev/md0 level=raid5 num-devices=3 metadata=0.90 spares=1 UUID=7ba24636:261b5ba5:d6f453eb:dfc5afa4
[root@f10-raid ~]# mdadm --detail /dev/md0
/dev/md0:
        Version : 0.90
  Creation Time : Sun Dec 14 15:01:47 2008
     Raid Level : raid5
     Array Size : 8176640 (7.80 GiB 8.37 GB)
  Used Dev Size : 4088320 (3.90 GiB 4.19 GB)
   Raid Devices : 3
  Total Devices : 3
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Tue Dec 16 21:54:43 2008
          State : clean
 Active Devices : 3
Working Devices : 3
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 256K

           UUID : 7ba24636:261b5ba5:d6f453eb:dfc5afa4
         Events : 0.880

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       18        1      active sync   /dev/sdb2
       2       8       34        2      active sync   /dev/sdc2

md0 was physical volume of VolGroup00 and VolGroup00 included LogVolume00 and LogVolume01 (/root and swap).

It worked perfectly, then I added sdd2 to md0 and started growing it:

mdadm --add /dev/md0 /dev/sdf1
mdadm --grow /dev/md0 --raid-devices=4

When it was a few per cent complete, I powered down the machine. After that, it didn't boot, saying

mdadm: no devices found for /dev/md0
  Reading all physical volumes.  This may take a while...
  Volume group "VolGroup00" not found
Unable to access resume device /dev/VolGroup00/LogVol01
mount: error mounting /dev/root on /sysroot as ext3: No such file or directory

I booted with Fedora DVD into rescue mode, copied the original mdadm.conf to /etc/mdadm.conf and here is what I tried:

# mdadm --assemble /dev/md0
mdadm: no devices found for /dev/md0
# mdadm --assemble /dev/md0 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2
mdadm: no devices found for /dev/md0
# mdadm --examine /dev/md0
mdadm: No md superblock detected on /dev/md0
# mdadm --examine /dev/sda2        #the same for sdb2/sdc2/sdd2
/dev/sda2:
          Magic : a92b4efc
        Version : 0.91.00
           UUID : 7ba24636:261b5ba5:d6f453eb:dfc5afa4
  Creation Time : Sun Dec 14 14:01:47 2008
     Raid Level : raid5
  Used Dev Size : 4088320 (3.90 GiB 4.19 GB)
     Array Size : 12264960 (11.70 GiB 12.56 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 0

  Reshape pos'n : 123648 (120.77 MiB 126.62 MB)
  Delta Devices : 1 (3->4)

    Update Time : Tue Dec 16 21:02:24 2008
          State : active
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0
       Checksum : 947a4a69 - correct
         Events : 927

         Layout : left-symmetric
     Chunk Size : 256K

      Number   Major   Minor   RaidDevice State
this     0       8        2        0      active sync   /dev/sda2

   0     0       8        2        0      active sync   /dev/sda2
   1     1       8       18        1      active sync   /dev/sdb2
   2     2       8       34        2      active sync   /dev/sdc2
   3     3       8       50        3      active sync   /dev/sdd2
# mdadm --grow --raid-disks=4 /dev/md0
mdadm: /dev/md0 is not an active md array - aborting

I see it's aware there was a reshape process in progress, but I don't know how to continue it.

Any ideas?

phosphide

[jeyno]

how did you get on ... I have a similar problem

[phosphide]

Unfortunately, I didn't
I'm still using RAID0 with some backups and I'm afraid of moving to an array I can't rely on (because I have no idea how to fix it when something goes wrong).

[sbingner]

# mdadm --assemble /dev/md0 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2

Perhaps it would have worked better if you tried to assemble it with the same devices you created it from.... such as:

# mdadm --assemble /dev/md0 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdf1

or was that a typo in your --add line?

You could also try adding the parameter -R

[phosphide]

It's over one year old, but I guess it's indeed a typo in the --add line (it typed some of the commands here manually, not copied it from terminal).

I moved to another city and only have a laptop here, so setting up RAID doesn't have much sense other than for testing purposes, but still I'd like to try RAID again when I have some free time.

Anyway, thanks for the answer!