I'd like to grow my RAID1 into a RAID5 by adding another hard drive, but the user interface won't allow me to do it. The "Grow" button is greyed out. It won't even let me add it as a hot spare.
I get this error:
Failed to execute command 'export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin; export LANG=C; mdadm --manage '/dev/md0' --add /dev/sde 2>&1' with exit code '1': mdadm: /dev/md0 has failed so using --add cannot work and might destroy mdadm: data on /dev/sde. You should stop the array and re-assemble it.