Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!aplcen!ginosko!gem.mps.ohio-state.edu!apple!bbn!news From: news@bbn.COM (News system owner ID) Newsgroups: comp.protocols.nfs Subject: Re: NFS not idempotent (was re: mountd Performance under Stress) Message-ID: <45735@bbn.COM> Date: 18 Sep 89 18:35:58 GMT References: <14068@bloom-beacon.MIT.EDU> <1211@sequent.cs.qmc.ac.uk> <45595@bbn.COM> Reply-To: pplaceway@izar.bbn.com (Paul W. Placeway) Organization: Bolt Beranek and Newman Inc., Cambridge MA Lines: 43 In article <45595@bbn.COM> pplaceway@izar.bbn.com (Paul W. Placeway) *I* wrote: < As near as I can tell, claiming that NFS ops are idempotent is nothing < more than "marketing blurf" from Sun marketing. The problem is that < Sun didn't think quite hard enough about what a remote file system has < to do before going off and writing one; and now we are stuck with it. I didn't really intend this to be flamable, but it came out that way. To those who are offended, I apologize. I don't mean to drag Sun through the mud, just point out that most of the world is using NFS v.2, and so here are these problems, some of which could have been caught in the original design and testing phases. Several things that NFS should (or could) do (NFS v.3 does at least some of these): The client should try to predict the servers mean delay time, a la Jacobson and Karels TCP timeout predictor. I believe NFS 3 does something like this. The client and server should both do something about reducing the read and write sizes in the face of a lot of failures, so the sys admin doesn't have to guess about the right size to set them in /etc/fstab. NFS has this split personality problem of being both a UNIX file system sharing system, and a heterogenous system file sharing system. It would be nice if more things could be done between like systems (so that I could mount another UNIX server's /dev just like RFS, but still mount normal files from VMS, VM, etc.). Some idea of levels and types of conformance would probably bridge the gap here. It would be _real_ nice to be able to set up two servers as a single, reliable, mirrored NFS file server. There are allready experimental systems to do this, but it would be nice if Sun developed one for general consumption. Whatever. More random ramblings from: -- Paul Placeway ,