Hello Michael, You can add 4 new drives to your MD1220 and create a new virtual disk.  You can also add drives and expand your virtual disk.  Once the drives are inserted you can use Open Manage or the controller bios to create your new virtual disk. Please let us know if you have any other questions.
We're needing to add storage to our PV MD122. We currently have 16 300-GB drives in RAID5 as one volume. Can I add 4 1-TB drives in RAID5 to the same PERC H800 adapter as a new volume, or do I need to add 8 more 300-GB drives and expend the current volume? Thank you for your help. ~ Michael
PowerVault MS1220