Kyle,
Is it possible that eight of the drives are under the control of a hardware RAID card?Such a card is not common but the E450 is just about the only system that ever used it.
If you indeed have a SRC/P adapter installed, then the drives are "hidden" by it and the card's RAID software is used to administer the disks.
Would it be possible for you to paste an entire prtdiag output here?
# /usr/platform/sun4u/sbin/prtdiag -v