On 4 March 2010 12:01, John Robinson [off-list ref] wrote:

On 04/03/2010 11:30, Alex Boag-Munroe wrote:

quoted

Hi guys...

Yes I am an idiot.  I was changing the chunk size of my RAID5 array
last night from 64kb to 256kb and left it running overnight.  During
the night we had a power outage.

This is where the idiot part comes in.  The backup file is on a
filesystem that's part of the RAID5 array, so obviously I am unable to
start it.  I completely forgot the filesystem I specified for
--backup-file was part of the same array.

Once you're all done pointing and laughing, can you let me know if I
am totally screwed?  I've a lot of data here that I -really- don't
want to lose...

Please help..

Idiot.

--
Alex Boag-Munroe

Lack of planning on your part does not constitute an emergency on mine.

OK, I was done pointing and laughing, until I saw your signature. Did you
choose that on purpose or did Gmail pick it for you?

I'm afraid I can't help with your problem, except to say that I've a feeling
you ought to be able to manually restart the half-reshaped array without the
backup file, so the worst case ought to be that you might lose one backup
file's worth of data. However, kernel and mdadm versions together with
output of `mdadm --detail` of your md device and `mdadm --examine` of its
constituent devices will help those more knowledgeable than me tell you what
to do next. If you're lucky the boss, Neil Brown, will help but I imagine
he's asleep right now since he lives in Australia and it's the middle of the
night there.

Best of luck,

John.

Hi John, thanks so much for your reply.

That is my signature and I stand by it, hence the whole "me idiot" and
not DEMANDING I get help etc.

mdadm is version 3.1.1.  New developments.  I found a post on the
internet where Neil recommended to someone to recreate the array
without erasing it.  Which I have done, mdadm starts the array and
mdadm -D shows that almost a terabyte of space is in use.

However, mdadm -D also shows a chunk size of 512k, which is neither
the 64k original chunk nor the 512k I asked for.

Kernel version is gentoo-sources-2.6.33.

Output of mdadm --examine for /dev/sda5 through /dev/sdd5:

/dev/sda5:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 17862986:014cb4c0:ffe6e849:786ed339 (local to host ncc-1701-e)
  Creation Time : Thu Mar  4 13:10:24 2010
     Raid Level : raid5
  Used Dev Size : 974767616 (929.61 GiB 998.16 GB)
     Array Size : 2924302848 (2788.83 GiB 2994.49 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1

    Update Time : Thu Mar  4 13:10:29 2010
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0
       Checksum : b951290 - correct
         Events : 3

         Layout : left-symmetric
     Chunk Size : 512K

      Number   Major   Minor   RaidDevice State
this     0       8        5        0      active sync   /dev/sda5

   0     0       8        5        0      active sync   /dev/sda5
   1     1       8       21        1      active sync   /dev/sdb5
   2     2       8       37        2      active sync   /dev/sdc5
   3     3       8       53        3      active sync   /dev/sdd5
/dev/sdb5:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 17862986:014cb4c0:ffe6e849:786ed339 (local to host ncc-1701-e)
  Creation Time : Thu Mar  4 13:10:24 2010
     Raid Level : raid5
  Used Dev Size : 974767616 (929.61 GiB 998.16 GB)
     Array Size : 2924302848 (2788.83 GiB 2994.49 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1

    Update Time : Thu Mar  4 13:10:29 2010
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0
       Checksum : b9512a2 - correct
         Events : 3

         Layout : left-symmetric
     Chunk Size : 512K

      Number   Major   Minor   RaidDevice State
this     1       8       21        1      active sync   /dev/sdb5

   0     0       8        5        0      active sync   /dev/sda5
   1     1       8       21        1      active sync   /dev/sdb5
   2     2       8       37        2      active sync   /dev/sdc5
   3     3       8       53        3      active sync   /dev/sdd5
/dev/sdc5:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 17862986:014cb4c0:ffe6e849:786ed339 (local to host ncc-1701-e)
  Creation Time : Thu Mar  4 13:10:24 2010
     Raid Level : raid5
  Used Dev Size : 974767616 (929.61 GiB 998.16 GB)
     Array Size : 2924302848 (2788.83 GiB 2994.49 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1

    Update Time : Thu Mar  4 13:10:29 2010
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0
       Checksum : b9512b4 - correct
         Events : 3

         Layout : left-symmetric
     Chunk Size : 512K

      Number   Major   Minor   RaidDevice State
this     2       8       37        2      active sync   /dev/sdc5

   0     0       8        5        0      active sync   /dev/sda5
   1     1       8       21        1      active sync   /dev/sdb5
   2     2       8       37        2      active sync   /dev/sdc5
   3     3       8       53        3      active sync   /dev/sdd5
/dev/sdd5:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : 17862986:014cb4c0:ffe6e849:786ed339 (local to host ncc-1701-e)
  Creation Time : Thu Mar  4 13:10:24 2010
     Raid Level : raid5
  Used Dev Size : 974767616 (929.61 GiB 998.16 GB)
     Array Size : 2924302848 (2788.83 GiB 2994.49 GB)
   Raid Devices : 4
  Total Devices : 4
Preferred Minor : 1

    Update Time : Thu Mar  4 13:10:29 2010
          State : clean
 Active Devices : 4
Working Devices : 4
 Failed Devices : 0
  Spare Devices : 0
       Checksum : b9512c6 - correct
         Events : 3

         Layout : left-symmetric
     Chunk Size : 512K

      Number   Major   Minor   RaidDevice State
this     3       8       53        3      active sync   /dev/sdd5

   0     0       8        5        0      active sync   /dev/sda5
   1     1       8       21        1      active sync   /dev/sdb5
   2     2       8       37        2      active sync   /dev/sdc5
   3     3       8       53        3      active sync   /dev/sdd5

Booting with autodetecting raid, states that there's no valid 0.9 superblock.

-- 
Alex Boag-Munroe

Lack of planning on your part does not constitute an emergency on mine.
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