Xref: utzoo comp.mail.misc:1307 comp.protocols.nfs:9 Path: utzoo!attcan!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!ukma!david From: david@ms.uky.edu (David Herron -- One of the vertebrae) Newsgroups: comp.mail.misc,comp.protocols.nfs Subject: Re: central mail server Keywords: mail NFS Message-ID: <10350@s.ms.uky.edu> Date: 10 Oct 88 04:13:54 GMT References: <363@asuvax.UUCP> <464@Terra.cc.brunel.ac.uk> <9449@swan.ulowell.edu> <71964@sun.uucp> <584@utkcs2.cs.utk.edu> Reply-To: david@ms.uky.edu (David Herron -- One of the vertebrae) Organization: U of Kentucky, Mathematical Sciences Lines: 47 I'm (now) one of the coordinators of the MMDF sources and am currently working on this problem ... in the context of MMDF. For this place where I am now we have a wide mix of machines. Vaxen of various shapes & sizes, a Sun server & some Sun workstations, a Sequent Balance, and a student lab full of 3b2's & 3b1's. It was felt that it would be 'nice' if, ignoring the 3b[21]'s, all our machines could have shared access to mailboxes, either through some POP like protocol or with NFS. The project to develop the POP-like protocol got abandoned. So, later I came up with a scheme to run under MMDF, which I am still testing out. I use NFS to access the mailbox directory. For file locking I have a directory (/usr/spool/mbxlckdir == MBXLCKDIR) into which I put lock files. (I made a little simplification here, the only files for which I'm providing this locking is the system mailboxes, the other mailboxes use the normal locking meaning that the locks only work within one particular system). There's some heuristics involved with the lock files, in the lock file I put the system name and pid of the owner, then later there are checks when someone else tries to acquire the lock. I went with this because 1) I was also wanting to support RFS with the same type of thing and I didn't know if RFS did locks across systems, 2) not all of our NFS's supported flock() anyway, and 3) for some reason I don't 'trust' across-the-net flock()s. Currently my heuristics don't work... I have to debug it, but I have to get time to go back to it. Also NFS errors (timeouts and the like) cause the mail readers to get confused. BUT, we are able to read mail across NFS and have it usually work. Possibly ALWAYS work with a little bit of effort put into the code. And it's really nice to be able to read mail from anywhere. It is possible that, for MMDF anyway, someone could fix up a copy of libmmdf.a & mail reader such that someone on a PC running PC-NFS (this could also be an Amiga with Ameristar TCP/IP/NFS) could send & read mail from their PC. Mailbox access would be across the net, and mail sending could be with either code that does SMTP or does the user-agent-to-submit protocol that MMDF uses internally. Again, across the network. I would be interested in seeing that capability, but don't have the time to develop it myself. -- <-- David Herron; an MMDF guy <-- ska: David le casse\*' {rutgers,uunet}!ukma!david, david@UKMA.BITNET <-- <-- "Smarter than the average pagan god ... "