Hello Marc Horowitz, since you wrote:
> Could someone explain to me why some people want to do *everthing*
> through the filesystem? AFS is great as a distributed filesystem, but
> it seems intuitively obvious that a protocol designed for handing
> mail, or news, or whatever, would be inherently better at that
> specific task.
You got stomped by sloppy formulation. What people want is to read
their e-mail. Now for some reasons incoming email is held in a single
file (per user), which is updated by:
o the mail delivery agent(s) when they add incoming mail
o all mail user agents reading the mailbox and removing messages
Proper interlocking of these updates is a file system issue, and afs
should be expected to handle it. Since unix does not provide for
interlocking below file level, many mail user agents:
o expect to do the locking themselves
o do it with incompatible protocols
The mail delivery agents also do it with incmpatible protocols, but
there are not so many of them, and they are usually managed by the
administrator and persuaded to do The Right Thing (tm).
We, for example, run only one delivery agent on the file server, which
therefore does interlock (with itself) correctly. The mail user agents
on the (NFS-) clients remove mail, but were written in an environment
that expects our delivery agent (sendmail) and interlocks with that
properly.
The user agents (elm, say) prohibit users running two copies of
themselves on one machine, and we tell users not to run two different
user agents on the same machine at the same time (easy) or on two
different machines (more difficult). So for us it sort of works
even for NFS, as long as users don't do stupid things which hurt them.
But there is a need for mail user agents that rely on the file system
to do the locking rather than trying to cook up their own, and they
would (of course) not run well at all under unix, but may run over AFS.
Thomas
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