MDADM Raid 5 > Raid 6 conversion error

[soljin2000]

Hey I am converting my
raid 5 array with 7 1 TB drives
in it to a
raid 6 with 10 1 TB drives

I have added the 3 new 1 TB drives and here is my MDADM output:

State : clean
Active Devices : 7
Working Devices : 10
Failed Devices : 0
Spare Devices : 3

Layout : left-symmetric
Chunk Size : 64K

UUID : 32962b85:88fd246e:ecb23616:6508cad3
Events : 0.2263814

Number Major Minor RaidDevice State
0 8 96 0 active sync /dev/sdg
1 8 32 1 active sync /dev/sdc
2 8 80 2 active sync /dev/sdf
3 8 112 3 active sync /dev/sdh
4 8 64 4 active sync /dev/sde
5 8 0 5 active sync /dev/sda
6 8 48 6 active sync /dev/sdd

7 8 160 - spare /dev/sdk
8 8 144 - spare /dev/sdj
9 8 128 - spare /dev/sdi

I am trying to run this command:
mdadm --grow /dev/md0 --level=6 --raid-devices=10 --backup-file=/md0.backup

I get this error:
mdadm: Cannot set device size/shape for /dev/md0: Invalid argument

I found an old post here:
http://www.issociate.de/board/post/4...grow_bug?.html

Suggesting that if I stop and remove the array then run this series of commands:

mdadm --stop /dev/md0
mdadm --remove /dev/md0
losetup -d /dev/loop1;losetup -d /dev/loop2;losetup -d /dev/
loop3;losetup -d /dev/loop4;losetup -d /dev/loop5
rm rd1 rd2 rd3 rd4 rd5

I can then perform the opertation successfully.

My question is:
Is the method I found likely to work?
If so will I be able to recover/reassemble the array afterwards keeping all the data?
Is there a better solution?
I MUST keep all the data and can't transfer all of it off somewhere else.

PS the server in question is running 10.10

Thanks for any help you can provide.

[soljin2000]

Solution found. That snip-it posted above has NOTHING to do with getting this grow to work.

1) Yes if you stop and remove an array you can reassemble it just fine with no data loss.

2) Stopping and starting the array is not the problem. Ubuntu as of 10.10 still has mdadm 2.6.7 as it's most up to date version. You have to HAND install a newer version of mdadm from here:

http://packages.debian.org/squeeze/mdadm

That will have what you need you can just wget that deb and run:

dpkg -i (the file you dled)

you will have to do some light reconfiguring then the grow command works perfectly.