Install the OS in one hard disk, and put the second one before turning
on the Server.

Now go to the root and type format, it will list you the hard disk
Number.
(i.e) c2t0d0 (Primary hard disk with partition info) and c2t1d0
(secondary disk)

http://www.nalanta.com/2008/08/21/di...ng-in-solaris/