As I recall, RFS was implemented over virtual circuits, whereas NFS was 
over datagrams (UDP).  RFS was well suited to Datakit, which only did 
virtual circuits, and they often were used together inside Bell Labs.  
One of the reasons NFS won is that IP won over Datakit.


On 01/10/2017 04:56 PM, Steve Simon wrote:
> There is also RFS, I think a USG package for SYSVr3. The paper I have
> About this is by Author L Sabsevitz, though I don’t know if he was the author
> of the code, or just the paper.
>
>