mdadm raid6 array reports incorrect size in df -h after grow

Question

I've recently grown a 5x 3tb mdadm raid6 array (8tb) with a sixth disc in fedora 18, and after full rebuild and check, "mdadm --detail /dev/md127" returns the below:

        Version : 1.2
  Creation Time : Sun Feb 10 22:01:32 2013
     Raid Level : raid6
     Array Size : 11720534016 (11177.57 GiB 12001.83 GB)
  Used Dev Size : 2930133504 (2794.39 GiB 3000.46 GB)
   Raid Devices : 6
  Total Devices : 6
    Persistence : Superblock is persistent
  Intent Bitmap : Internal
    Update Time : Sun Jul 21 17:31:32 2013
          State : active 
 Active Devices : 6
Working Devices : 6
 Failed Devices : 0
  Spare Devices : 0
         Layout : left-symmetric
     Chunk Size : 512K
           Name : ubuntu:tercore
           UUID : f52477e1:ded036fa:95632986:dcb84e51
         Events : 326236
    Number   Major   Minor   RaidDevice State
       0       8        1        0      active sync   /dev/sda1
       1       8       17        1      active sync   /dev/sdb1
       2       8       33        2      active sync   /dev/sdc1
       4       8       49        3      active sync   /dev/sdd1
       5       8       80        4      active sync   /dev/sdf
       6       8       64        5      active sync   /dev/sde

All good.

I then ran "cat /proc/mdstat" which returned the below:

Personalities : [raid6] [raid5] [raid4] 
md127 : active raid6 sde[6] sdf[5] sda1[0] sdb1[1] sdd1[4] sdc1[2]
      11720534016 blocks super 1.2 level 6, 512k chunk, algorithm 2 [6/6] [UUUUUU]
      bitmap: 0/22 pages [0KB], 65536KB chunk
unused devices: <none>

Also fine.

However when running "df -h" I get the below, which incorrectly reports the old raid capacity:

Filesystem                           Size  Used Avail Use% Mounted on
devtmpfs                             922M     0  922M   0% /dev
tmpfs                                939M  140K  939M   1% /dev/shm
tmpfs                                939M  2.6M  936M   1% /run
tmpfs                                939M     0  939M   0% /sys/fs/cgroup
/dev/mapper/fedora_faufnir--hp-root   26G  7.2G   17G  30% /
tmpfs                                939M   20K  939M   1% /tmp
/dev/sdg1                            485M  108M  352M  24% /boot
/dev/md127                           8.2T  7.6T  135G  99% /home/teracore

Can anyone help me fix this mismatch? It's also naturally causing samba to report the incorrect array capacity via my windows laptop too.

Many thanks in advance! Will.

what file system is on the /dev/md127 ? Did you use resize2fs after rebuid? — ALex_hha, Jul 21 '13 at 17:32

score 1 · Accepted Answer · answered Jul 21 '13 at 18:09

I think you forget to execute resize2fs command

# mdadm --detail /dev/md0
/dev/md0:
        Version : 0.90
  Creation Time : Sun Jul 21 23:50:49 2013
     Raid Level : raid6
     Array Size : 62914368 (60.00 GiB 64.42 GB)
  Used Dev Size : 20971456 (20.00 GiB 21.47 GB)
   Raid Devices : 5
  Total Devices : 5
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Mon Jul 22 00:04:43 2013
          State : clean
 Active Devices : 5
Working Devices : 5
 Failed Devices : 0
  Spare Devices : 0

     Chunk Size : 64K

           UUID : c0a5733d:46d5dd5e:b24ac321:6c547228
         Events : 0.13992

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       2       8       48        2      active sync   /dev/sdd
       3       8       64        3      active sync   /dev/sde
       4       8       80        4      active sync   /dev/sdf

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              39G  1.6G   35G   5% /
/dev/sda1             494M   23M  446M   5% /boot
tmpfs                 500M     0  500M   0% /dev/shm
/dev/md0               60G  188M   59G   1% /raid6

# resize2fs /dev/md0
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/md0 is mounted on /raid6; on-line resizing required
Performing an on-line resize of /dev/md0 to 20971456 (4k) blocks.
The filesystem on /dev/md0 is now 20971456 blocks long.

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              39G  1.6G   35G   5% /
/dev/sda1             494M   23M  446M   5% /boot
tmpfs                 500M     0  500M   0% /dev/shm
/dev/md0               79G  192M   79G   1% /raid6

# mdadm --detail /dev/md0
/dev/md0:
        Version : 0.90
  Creation Time : Sun Jul 21 23:50:49 2013
     Raid Level : raid6
     Array Size : 83885824 (80.00 GiB 85.90 GB)
  Used Dev Size : 20971456 (20.00 GiB 21.47 GB)
   Raid Devices : 6
  Total Devices : 6
Preferred Minor : 0
    Persistence : Superblock is persistent

    Update Time : Mon Jul 22 00:04:43 2013
          State : clean
 Active Devices : 6
Working Devices : 6
 Failed Devices : 0
  Spare Devices : 0

     Chunk Size : 64K

           UUID : c0a5733d:46d5dd5e:b24ac321:6c547228
         Events : 0.13992

    Number   Major   Minor   RaidDevice State
       0       8       16        0      active sync   /dev/sdb
       1       8       32        1      active sync   /dev/sdc
       2       8       48        2      active sync   /dev/sdd
       3       8       64        3      active sync   /dev/sde
       4       8       80        4      active sync   /dev/sdf
       5       8       96        5      active sync   /dev/sdg

P.S. I will suggest to unmount /dev/md127 before resize operation

Great, thanks, running now, would you have any idea how long it might take for an array this size? — Faufnir, Jul 21 '13 at 19:32
Ignore that, just finished up and worked like a charm, thanks again! :) — Faufnir, Jul 21 '13 at 19:47

mdadm raid6 array reports incorrect size in df -h after grow

1 Answers1