PS: Dunno why yourself and Piru keep saying the sector size is fixed at 512 bytes...
Hard disk sector size is fixed by the manufacturer, file system block size can be changed to any whole number of sectors. Unfortunately the words blocks and sectors are used as synonyms in many places or even mixed up.
As I understand it, the maximum partition size of SFS calculates from the file system block size. So you are right in this regard.
