a (hopefully) simple newbie zfs query regarding available space

[John .]

Hello list

I followed instructions for ZFS on
http://wiki.freebsd.org/ZFSQuickStartGuide, substituting ad6 and ad10
(two new SATA3 1TB disks) for da0 da1 and da2 in the instructions. I
was surprised to see only 993GB in /tank/. Is this expected, or is it
user error? Also, these disks are completely unformatted. I expected
to do a newfs or something similar, and for it to take a bit of time!

This is on a running 7.2-STABLE amd64 system. It is only these two
disks that I want as ZFS, the rest are UFS2

cheers
-- 
John