You may be better off using PFS-060ds (Direct SCSI) If you're running Workbench 3.1, otherwise you'll be limited to just under 4gb of Hard disk space :-
When adding the filesystem to the RDB, if you're not using the standard FastFileSystem, you have to change the identifier number to suit the selected filesystem,
If you are running OS 3.1 or earlier, you may be better off using 'HDInstTools' From Aminet as 3.1's HDToolbox doesn't always recognise large drives, and may read them as a totally different size.
Let us know if you're using 3.1 or above and we can go from there :-)
Robert.