Re: Data Offset

Hello. I have an issue concerning a broken RAID of unsure pedigree.
Examining the drives tells me the block sizes are not the same, as
listed in the email.

I certainly won't be easy.  Though if someone did find themselves in that
situation it might motivate me to enhance mdadm in some way to make it easily
fixable.

I seem to be your motivation for making this situation fixable.
Somehow I managed to get drives with an invalid block size. All worked
fine until a drive dropped out of the RAID5. When attempting to
replace, I can re-create the RAID, but it cannot be of the same size
because the 1024-sector drives are "too small" when changed to
2048-sector, exactly as described. Are there any recovery options I
could try, including simply editing the header?


mdadm --examine of all drives in the RAID:

/dev/sdb3:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 9759ad94:75e30b6b:8a726b4d:177a6eda
           Name : leyline:1  (local to host leyline)
  Creation Time : Mon Sep 12 13:19:00 2011
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 3906525098 (1862.78 GiB 2000.14 GB)
     Array Size : 15626096640 (7451.10 GiB 8000.56 GB)
  Used Dev Size : 3906524160 (1862.78 GiB 2000.14 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
          State : clean
    Device UUID : 872097fa:3ae66ab4:ed21256a:10a030c9

    Update Time : Fri Jun  1 03:11:54 2012
       Checksum : 6d627f7a - correct
         Events : 2127454

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 1
   Array State : AAAA. ('A' == active, '.' == missing)

          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 9759ad94:75e30b6b:8a726b4d:177a6eda
           Name : leyline:1  (local to host leyline)
  Creation Time : Mon Sep 12 13:19:00 2011
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 3906525098 (1862.78 GiB 2000.14 GB)
     Array Size : 15626096640 (7451.10 GiB 8000.56 GB)
  Used Dev Size : 3906524160 (1862.78 GiB 2000.14 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
          State : clean
    Device UUID : 2ea285a1:a2342c24:ffec56a2:ba6fcf07

    Update Time : Fri Jun  1 03:11:54 2012
       Checksum : fae2ea42 - correct
         Events : 2127454

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 0
   Array State : AAAA. ('A' == active, '.' == missing)

/dev/sdc3:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 9759ad94:75e30b6b:8a726b4d:177a6eda
           Name : leyline:1  (local to host leyline)
  Creation Time : Mon Sep 12 13:19:00 2011
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 3906525098 (1862.78 GiB 2000.14 GB)
     Array Size : 15626096640 (7451.10 GiB 8000.56 GB)
  Used Dev Size : 3906524160 (1862.78 GiB 2000.14 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
          State : clean
    Device UUID : 2ea285a1:a2342c24:ffec56a2:ba6fcf07

    Update Time : Fri Jun  1 03:11:54 2012
       Checksum : fae2ea42 - correct
         Events : 2127454

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 0
   Array State : AAAA. ('A' == active, '.' == missing)


/dev/sdd3:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 9759ad94:75e30b6b:8a726b4d:177a6eda
           Name : leyline:1  (local to host leyline)
  Creation Time : Mon Sep 12 13:19:00 2011
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 3906524160 (1862.78 GiB 2000.14 GB)
     Array Size : 15626096640 (7451.10 GiB 8000.56 GB)
    Data Offset : 1024 sectors
   Super Offset : 8 sectors
          State : clean
    Device UUID : 8d656a1d:bbb1da37:edaf4011:1af2bbb9

    Update Time : Fri Jun  1 03:11:54 2012
       Checksum : ab4c6863 - correct
         Events : 2127454

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : Active device 3
   Array State : AAAA. ('A' == active, '.' == missing)

/dev/sde3:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 9759ad94:75e30b6b:8a726b4d:177a6eda
           Name : leyline:1  (local to host leyline)
  Creation Time : Mon Sep 12 13:19:00 2011
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 3906524160 (1862.78 GiB 2000.14 GB)
     Array Size : 15626096640 (7451.10 GiB 8000.56 GB)
    Data Offset : 1024 sectors
   Super Offset : 8 sectors
          State : clean
    Device UUID : 37bb83bd:313c9381:cabff9d0:60bd205c

    Update Time : Wed May 23 03:30:50 2012
       Checksum : f72e6959 - correct
         Events : 2004256

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : spare
   Array State : AAAA. ('A' == active, '.' == missing)

/dev/sdf:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : 9759ad94:75e30b6b:8a726b4d:177a6eda
           Name : leyline:1  (local to host leyline)
  Creation Time : Mon Sep 12 13:19:00 2011
     Raid Level : raid5
   Raid Devices : 5

 Avail Dev Size : 3907027120 (1863.02 GiB 2000.40 GB)
     Array Size : 15626096640 (7451.10 GiB 8000.56 GB)
  Used Dev Size : 3906524160 (1862.78 GiB 2000.14 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
          State : clean
    Device UUID : e16d4103:cd11cc3b:bb6ee12e:5ad0a6e9

    Update Time : Fri Jun  1 03:11:54 2012
       Checksum : e287a82a - correct
         Events : 0

         Layout : left-symmetric
     Chunk Size : 512K

   Device Role : spare
   Array State : AAAA. ('A' == active, '.' == missing)

--
James Moore

--
James Moore
--
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