Mikael Abrahamsson <swmike <at> swm.pp.se> writes:

On Wed, 26 Mar 2014, Tide wrote:

quoted

The partition size of each disk in the two arrays are identical (all 
partitions have 5860531087 logical sectors), so why the array size are 
different? Is it caused by different mdadm version (I guess so) or 
different array level or something else?

Do mdadm -E on one component device from each md volume. My first guess 
would be different data offset.

Yes, the data offset are different. But why? When creating array, I didn't
specified any other options:
mdadm -C /dev/md127 -l 5 -n 3 /dev/sd[bcd]1
mdadm --add /dev/md127 /dev/sd[ef]1
mdadm --grow /dev/md127 -n 4

mdadm -C /dev/md127 -l 6 -n 5 /dev/sd[bcdef]1

=================
Array 1 (RAID 5):
=================
# mdadm --examine /dev/sdb1
/dev/sdb1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x0
     Array UUID : dfd3bbe7:4b0231fe:9007bc4a:e106acac
           Name : RecordBackup01:127  (local to host RecordBackup01)
  Creation Time : Fri Jan 11 17:56:18 2013
     Raid Level : raid5
   Raid Devices : 4

 Avail Dev Size : 5860529039 (2794.52 GiB 3000.59 GB)
     Array Size : 8790792192 (8383.55 GiB 9001.77 GB)
  Used Dev Size : 5860528128 (2794.52 GiB 3000.59 GB)
    Data Offset : 2048 sectors
   Super Offset : 8 sectors
   Unused Space : before=1968 sectors, after=911 sectors
          State : active
    Device UUID : 85fa01f1:b8e7875c:5f19039f:b198c0bb

    Update Time : Thu Mar 27 03:35:06 2014
       Checksum : 16ff8ff5 - correct
         Events : 7266

         Layout : left-symmetric
     Chunk Size : 512K

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


=================
Array 2 (RAID 6):
=================
# mdadm --examine /dev/sdb1
/dev/sdb1:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : 923c9658:12739258:506fc8b0:f8c5edf3
           Name : RecordBackup02:127  (local to host RecordBackup02)
  Creation Time : Fri Mar 21 18:12:00 2014
     Raid Level : raid6
   Raid Devices : 5

 Avail Dev Size : 5860268943 (2794.39 GiB 3000.46 GB)
     Array Size : 8790402048 (8383.18 GiB 9001.37 GB)
  Used Dev Size : 5860268032 (2794.39 GiB 3000.46 GB)
    Data Offset : 262144 sectors
   Super Offset : 8 sectors
   Unused Space : before=262056 sectors, after=911 sectors
          State : clean
    Device UUID : 94a83f3f:33991f7a:9545d12f:87bd169f

Internal Bitmap : 8 sectors from superblock
    Update Time : Thu Mar 27 01:55:49 2014
  Bad Block Log : 512 entries available at offset 72 sectors
       Checksum : 5a7094a4 - correct
         Events : 8178

         Layout : left-symmetric
     Chunk Size : 512K

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