A colleague of mine was trying to duplicate the partition table of the primary disk onto the backup hard drive (same size, same brand/model). I mentioned using prtvtoc command to display the Volume Table of Contents and then pipe its output to the fmthard command. Unfortunately, he was already populating the second hard drive via the manual process. At any rate, here is an example.
# prtvtoc /dev/rdsk/c1t10d0s2 | fmthard -s - /dev/rdsk/c1t11d0s2