glass@mica.berkeley.edu (07/29/89)
I've been asked to write an essay on how clusters of diskless
UNIX workstations manage to share file systems -- without
stepping on one another's "toes" and maintaining their individual
identities.
There are two issues here. The first is: How do manufacturers
arrange the file system so that the files which give the machines
their individual identities appear different to each machine,
while others are shared? Remember that, due to the ad-hoc growth
of UNIX, many configuration files are in the same directories as
data files, utilities, and applications that can and should be
shared.
Second, how does a server handle diskless clients with different
architectures (or running different versions of the OS)? For
example, a Sun 4 can't use the same binaries as a Sun 3 -- and if
the server is a VAX, it will need separate binaries as well.
I've begun to get a handle on how Sun addresses this problem in
SunOS 4.0 (though more info would be welcome). However, I have no
idea how (or if) Apollo, ULTRIX, HP, Sequent (which really is a
network in a box), AIX, A/UX, POSIX, and OSF propose to handle
these problems. (I have heard that the Apollo machines implement
some trick whereby environment variables can be included in the
pathnames of files, but the person who mentioned this to me
didn't know any of the details, nor how pervasive this technique
was.)
If you have insights on how any or all UNIX implementations
address these problems, please respond to this posting and/or
send me mail. I'm sending this query to a broad cross-section of
newsgroups in an attempt to learn about many different
techniques, but since following up to all those groups would
cause a great deal of traffic, I've set the Followup-To: line to
point at comp.unix.questions. I will summarize (and perhaps
interject some ideas) in the essay, which I hope to publish
shortly.
============================================================================
"One of the nicest things about mathematics, or anything else you might
care to learn, is that many of the things which can never be, often are."
Norton Juster, "The Phantom Tollbooth"
============================================================================