I have a RAID60 that I want to expand.
The current is: 2 axles each having 9 disks + 2 spares.
The future is: 4 axles each having 10 disks + 1 spare.
So I need to do some --grow to reshape the drives.
I thought this would be enough:
mdadm -v --grow /dev/md1 --raid-devices=10 --backup-file=/root/back-md1
mdadm -v --grow /dev/md2 --raid-devices=10 --backup-file=/root/back-md2
mdadm -v --grow /dev/md0 --raid-devices=4 --add /dev/md3 /dev/md4
The last command works, but the 2 first commands fail with:
mdadm: Need to backup 7168K of critical section..
mdadm: /dev/md2: Something wrong - reshape aborted
How can I --grow a RAID6 to use more devices?
Info about the system:
$ mdadm --version
mdadm - v3.2.5 - 18th May 2012
$ uname -r
3.5.0-17-generic
Makefile to reproduce the problem:
all: install_parallel createmd0 createmd3 createmd4
install_parallel:
parallel --version || wget -O - pi.dk/3 | bash
loop:
# make enough loop-devices
seq 0 50 | parallel mknod -m 660 /dev/loop{} b 7 {} || true
seq 0 50 | parallel dd if=/dev/zero of=l{} bs=1M count=1
seq 0 50 | parallel losetup -f l{}
createmd1: loop
mdadm --create /dev/md1 -c 128 --level=6 --raid-devices=9 -x 2 /dev/loop1? /dev/loop1
createmd2: loop
mdadm --create /dev/md2 -c 128 --level=6 --raid-devices=9 -x 2 /dev/loop2? /dev/loop2
createmd3: loop
mdadm --create /dev/md3 -c 128 --level=6 --raid-devices=10 -x 1 /dev/loop3? /dev/loop3
createmd4: loop
mdadm --create /dev/md4 -c 128 --level=6 --raid-devices=10 -x 1 /dev/loop4? /dev/loop4
createmd0: loop createmd1 createmd2
mdadm --create /dev/md0 -c 512 --level=0 --raid-devices=2 /dev/md1 /dev/md2
grow:
mdadm -v --grow /dev/md1 --raid-devices=10 --backup-file=/root/back-md1
mdadm -v --grow /dev/md2 --raid-devices=10 --backup-file=/root/back-md2
mdadm -v --grow /dev/md0 --raid-devices=4 --add /dev/md3 /dev/md4
info:
mdadm --version
uname -r
clean:
mdadm --stop /dev/md0 /dev/md? || true
seq 0 50 | parallel losetup -d /dev/loop{} || true
seq 0 50 | parallel rm l{}
