The 4GB limit is a limitation of the interface between the device driver (scsi.device) and the file system (SFS). The standard interface as used in the Kickstart ROM uses 32bit addresses, so up to 2^32 bytes (4GB) can be addressed.
However, even with the ROM device driver you can use SCSI commands. This is usualy referred to as SCSI-Direct or as HD_SCSICMD. With this interface you can theoretically address 2TB (2^32 blocks of 512 bytes each). Due to a bug the Kickstart driver can only address up to 8GB.
The way to completely overcome the 4GB limit is to introduce a new interface. This has been done by two companies. One introduced TD64 commands, the other introduced NSD. Both require a new scsi.device which is installed by IDEfix97 and OS3.5+.
Well, SFS up to version 1.84 supported all three possibilities: NSD, TD64 and Direct-SCSI. Version 1.87 (or 1.187) dropped Direct-SCSI support. You can read this in the SFS history file.
So with a standard equipped OS3.1 Amiga you can only use 8GB with SFS up to version 1.84 and 4GB with SFS from version 1.87 onwards (I don't remember if 1.85 and 1.86 exist). Only with a patch for scsi.device you can use bigger HDDs.
Things are looking totally different if you don't use the internal IDE bus. For example the Phase5 SCSI controllers all support TD64, so you don't need any patch and can use HDDs of any size with every version of SFS at once. Elbox' FastATA does so either.
I assume there are other SCSI or IDE controllers for which no patch exists and which do not support any 64bit commands, so these won't ever be able to handle HDDs larger than 4GB. However, the SCSI-Direct approach might help here.
Bye,
Thomas
Addition:
Lost this feature? Why? In the SFS website, I read that there is no limit considering partitions! Now I need to install IDEFix as well!
Well, to take your sentence strictly as it is written, it is correct: there is no limit considering *partitions*. The 4GB limit limits the *HDD* size, not the partition size. :-D
