Take the 2-minute tour ×
Server Fault is a question and answer site for professional system and network administrators. It's 100% free, no registration required.

mdadm - v3.2.5 - 18th May 2012

Currently have:

        Version : 1.2
  Creation Time : Tue Jun 25 19:03:31 2013
     Raid Level : raid5
     Array Size : 2930135040 (2794.39 GiB 3000.46 GB)
  Used Dev Size : 2930135040 (2794.39 GiB 3000.46 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

    Update Time : Wed Jun 26 17:17:01 2013
          State : clean 
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

         Layout : left-symmetric
     Chunk Size : 512K

           Name : desktop:0  (local to host desktop)
           UUID : 91a6c44d:21226975:8d2dc41a:7fcff414
         Events : 7434

    Number   Major   Minor   RaidDevice State
       2       8       16        0      active sync   /dev/sdb
       1       8       48        1      active sync   /dev/sdd

Problem:

/dev/sdc is full of data.

I want to grow the raid to 3 devices in degraded state (therefore 6TB), copy all the data to the raid. Then actually add /dev/sdc.

Already tried:

andey@desktop:~$ sudo mdadm --add /dev/md127 missing
mdadm: 'missing' only meaningful with --re-add

andey@desktop:~$ sudo mdadm --re-add /dev/md127 missing

No complaints from mdadm, however when I checked the RAID there wasn't a third drive


andey@desktop:~$ sudo mdadm --grow /dev/md127 --raid-devices=3
mdadm: Need 1 spare to avoid degraded array, and only have 0.
       Use --force to over-ride this check.
andey@desktop:~$ sudo mdadm --grow /dev/md127 --raid-devices=3 --force
mdadm: Need to backup 1024K of critical section..
mdadm: /dev/md127: Cannot grow - need a spare or backup-file to backup critical section
share|improve this question

1 Answer 1

up vote 1 down vote accepted

You are almost there. Now use the --backup-file option to specify a temp file for mdadm to use. Do not put it on your md array.

share|improve this answer
    
Thanks, worked perfectly –  Andrew Wei Jun 27 '13 at 1:43

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.