On Mon, 21 Dec 2009 03:41:33 +0000
Kristleifur Daðason [off-list ref] wrote:

Hi all,

I wish to convert my 3-drive RAID-5 array to a 6-drive RAID-6. I'm on
Linux 2.6.32.2 and have mdadm version 3.1.1 with the 32-bit-array-size
patch from here: http://osdir.com/ml/linux-raid/2009-11/msg00534.html

I have three live drives and three spares added to the array. When I
initialize the command, mdadm does the initial checks and aborts with
a "cannot set device shape" without doing anything to the array.

Following are some md stats and growth command output:

___

$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5]
[raid4] [raid10]
md_d1 : active raid5 sdd1[6](S) sdc1[5](S) sdb1[4](S) sdf1[1] sde1[0] sdl1[3]
      2930078720 blocks super 1.1 level 5, 256k chunk, algorithm 2 [3/3] [UUU]
      bitmap: 1/350 pages [4KB], 2048KB chunk

$ mdadm --detail --scan
ARRAY /dev/md/d1 metadata=1.01 spares=3 name=mamma:d1
UUID=da547022:042a6f68:d5fe251e:5e89f263

$ mdadm --grow /dev/md_d1 --level=6 --raid-devices=6
--backup-file=/root/backup.md1_to_r6
mdadm: metadata format 1.10 unknown, ignored.
mdadm: metadata format 1.10 unknown, ignored.
mdadm level of /dev/md_d1 changed to raid6
mdadm: Need to backup 1024K of critical section..
mdadm: Cannot set device shape for /dev/md_d1
mdadm: aborting level change
___


Three questions -

1. What does the stuff about "metadata format 1.10 unknown" mean?
Notice the "super 1.1" vs. "metadata 1.01" vs. "metadata format 1.10"
disrepancy between mdsat, --detail and --grow output.

The metadata format .. unknown means that your /etc/mdadm.conf contains
something like
       metadata=1.10

2. Am I doing something wrong? :)

Not obviously.

3. How can I get more info about what is causing the failure to
initialize the growth?

Look in the kernel logs.  e.g. 
   dmesg | tail -20

immediately after the "mdadm --grow" attempt.

I just tried the same thing and it worked for me.

NeilBrown
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