Path: utzoo!attcan!uunet!lll-winken!ncis.llnl.gov!helios.ee.lbl.gov!pasteur!agate!bionet!csd4.milw.wisc.edu!mailrus!uflorida!haven!uvaarpa!mcnc!rti!mcm From: mcm@rti.UUCP (Mike Mitchell) Newsgroups: comp.dcom.lans Subject: Re: NFS vs RFS Message-ID: <2735@rti.UUCP> Date: 20 Jan 89 17:21:27 GMT References: <9018@cit-vax.Caltech.Edu> <7387@chinet.chi.il.us> <437@aurora.AthabascaU.CA> <340@moriaMoria.Sp.Unisys.Com> <709@atanasoff.cs.iastate.edu> Reply-To: mcm@rti.UUCP (Mike Mitchell) Organization: Research Triangle Institute, RTP, NC Lines: 69 Here is a table that I have made for my own comparisons: CRITERIA RFS NFS -------------------------------------------------------------------------------- Operating multivendor hardware; multivendor hardware; Environments System V only; BSD, System V, hybrids, VMS server, MS-DOS client; multiple networking protocols multiple networking protocols -------------------------------------------------------------------------------- Implementation in-kernel; in-kernel; stateful server; stateless server; at inode interface at inode interface -------------------------------------------------------------------------------- Transparency remote file access; remote file access; remote device access (but see below) -------------------------------------------------------------------------------- UNIX semantics preserves all UNIX does not preserve all file system semantics UNIX file system semantics -------------------------------------------------------------------------------- Reliability/ no single failure point; no single failure point; Data Integrity append mode works; append mode may not work; atomic writes work; atomic writes may not work; open files will not be open files can be erroneously deleted while in use; deleted while in use; file systems cannot be file systems can be inadvertently unmounted inadvertently unmounted while in use while in use -------------------------------------------------------------------------------- Concurrency supports lockf file locking not directly file locking mechanism supported (requires separate stateful 'lock server') -------------------------------------------------------------------------------- Security provides tools to limit network security degenerates access by user id to that of least secure system -------------------------------------------------------------------------------- Much of this information is from an article in UNIX/WORLD, entitled "AT&T's RFS and SUN's NFS: A Comparison of Heterogeneous Distributed File Systems." The article was written by Mark J. Hatch, Michael Katz, and Jim Rees. I find it very strange that NFS insists that stateless servers are the best, but then has to add statefull servers to handle locking and other things. NFS claims to work in a heterogeneous UNIX environment, but to do that each hardware vendor has had to re-write their operating system. They get the template to do the re-write from SUN, so it seems to me that NFS gets around heterogeneity problems by making everyone run the same OS. Now everything is homogeneous as far as NFS is concerned. RFS has some problems too. It also aproaches heterogeneity problems by making everyone run the same code. It is not available from as many vendors as NFS is, and it has not been out on the market as long as NFS. NFS has had time to work some of the bugs out, while RFS is still a little new. We don't have any machines at our shop that can run RFS, so I don't know how easy it is to set up. We have a few machines with NFS compiled in, but we don't use NFS either. I think that RFS is technically superior to NFS, but NFS has a marketing advantage. NFS is available on many more machines than RFS, so choosing which to use is easier. There are a few companies that have chosen to go their own route with distributed computing, and not use either NFS or RFS. Some of their offerings are quite good, but I'm not sure how they will hold up to the marketing pressure NFS and RFS will bring to bear. -- Mike Mitchell {decvax,seismo,ihnp4,philabs}!mcnc!rti!mcm mcm@rti.rti.org "There's laughter where I used to see a tear. w (919) 541-6098 It's all done with mirrors, have no fear." h (919) 361-2048