# Make a raid1, add a device, then remove it again. mdadm -CR $md0 -l1 -n2 -x1 $dev0 $dev1 $dev2 check resync check wait check state UU mdadm --grow $md0 -n 3 check recovery check wait check state UUU mdadm $md0 --fail $dev0 check state _UU mdadm --grow $md0 -n 2 check state UU mdadm -S $md0 # same again for version-1 mdadm -CR $md0 -l1 -n2 -e1.2 -x1 $dev0 $dev1 $dev2 check resync check wait check state UU mdadm --grow $md0 -n 3 check recovery check wait check state UUU mdadm $md0 --fail $dev0 check state _UU mdadm --grow $md0 -n 2 check state UU mdadm -S $md0