What bellnexxia says is true, but you should clarify what your boss wants. Does he mean a 'mirrored' disk, or a 'backup' disk. The mirrored disk is maintained by the Suite at all times like in RAID 1 (is that right?), while the backup disk is as the name suggests a backup of your system disk taken once (or once in a while if you prefer) using something like ufsdump.
Hope this helps.
- Stuart