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:
redacted

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.