Novell LINUX ENTERPRISE SERVER 11 - STORAGE ADMINISTRATION GUIDE 2-23-2010 Administration Manual page 107

mdadm -D /dev/md0 | grep -e "Array Size" -e "Device Size"
5 Do one of the following:
If your array was successfully resized, you are done.
If your array was not resized as you expected, you must reboot, then try this procedure
again.
Resizing Software RAID Arrays with mdadm 107