HAST different disk sizes

The documentation for HAST assumes that the disks being used are of 
identical size.  In the real world, this rarely happens.  How are disks of 
different sizes handled? In my case, on drive is about 1TB and one is 
about 500GB.

Is it possible to run HAST on a partition?  All the examles show it 
running on the raw device (/dev/da0, for example).

I guess if the answer to the second question is "yes, you can run HAST on 
a partition", then it also answers my first question.

I'm sorry if this is the wrong list.  freebsd-cluster seems to be dormant 
except for spam.