Re: [TUHS] RFS was: Re: UNIX of choice these days?

I have some first hand experience with this.... in 1984. Valid Logic Systems Inc, an early VLSI design vendor hired me as a contractor to fix bugs in this funky ethernet driver they had (from Lucas films, IIRC) that did some remote file operations. I proposed that instead I do a "proper" networked file system and to my amazement they agreed to let me build a prototype. I first built an RPC layer (ethertype 1600 -- see RFC 1700!) and then EFS (extended FS) that allowed access to remote files. Being a one man team I punted on generality. Just hand-built separate marshall/unmarshall function for each remote procedure. No mounts. Every node's FS was visible to everyone else (subject to Unix permissions). /net/ path prefix was for remote files. All this took about 2-3 months. Performance was decent for a 1984 era workstation. Encouraged by the progress I suggested we add in missing functionality such as the ability to chdir to a remote dir etc. Yes, state! And complications! On bootup every node advertized its presence & a "generation" number (incremented by 1 from the last gen) so that other nodes can drop old outstanding state -- not unlike a disk dying but still messy to clean things up. Next had to make scheduling priority for remote operations to be interruptible. People didn't like "cd /net/foo" hanging indefinitely! unlink and mv were a problem (machine A wouldn't know if machine B did this). rm was easy to fix -- just add a refcount for every remote machine with an open. mv not so. I don't think I ever solved this. Local FS read/write are atomic so I tried very hard to make the remote read/writes atomic as well. This can get interesting in presence of a node crashing.... At about this time, Sun gave a presentation on NFS to Valid. I suspect Valid also realized that doing this properly was a much bigger than a one man project. Result: they terminated the project. It was a fun project while it lasted. The fact this much was done was thanks to a lot of invaluable help from my friend Jamie Markevitch (also a contractor @ Valid at that point). At the time I thought all of these stateful problems were solvable given more time but now I am not so sure. But as a result of that belief I never really liked NFS. I felt they took the easy way out.