The first partition (boot) must be less than 2GB and the whole hard disk must be smaller than 2 Terrabyte.
However this is FFS limitations, many IDE interfaces have their own further constraints.
On the
FastATA MKIII here, I am running 32.2GB non boot partitions without problem on a 250GB hard disk with FFS v45.13.
Be aware of limitations of other filesystems for example such as Professional Filesystem (PFS) which can only address a hard disk < 127GB.
