PUP under UNIX

[Barry Shein]

[a few people ask about using their 4.2 systems as X1108 fileservers:]

Briefly, we run PUP under 4.2bsd/VAX here at BU to support our 1108
Xerox Lisp machines. The software is available from Xerox and works
quite well, it essentially implements a network file system for your
lisp machine, for example I can:

	CONN {BUCSB}</usr3/bzs>

thus making that UNIX directory be my current directory and any file
saving, loading, compiling etc occurs to/from that directory (which is
nice as the backup schedule on that machine is more regular than the
local lisp machine's disk.) You can put all your fonts and other common
binaries etc out on the UNIX file system and just point to them with
your init file (eg. (SETQ FONTDIRECTORIES '({BUCSB}</usr2/dlion/fonts>)))
or whatver the interlisp var is, I think that's right.) Thus it's easy
for N machines to share those areas (and also for a user to walk up to
any lisp machine without needing to have their files local.) Yes, it's
a big win, do it, it requires a little kernel hacking but nothing major.
Of course, you can OPEN files etc remotely via the same pathname syntax.
We have also booted SYSOUTs over the net tho this is a little slo (tho
the other choice is often a handful of floppies so it still can be a big
win under the right circumstances.)

As far as XNS goes, I don't believe LEAF is available yet under XNS for
UNIX which is what is accomplishing all that magic, so you probably want
PUP whether or not you will be moving to the 4.3 XNS in the near future
(good question: is anything beyond IDP and SPP provided with the 4.3
distribution? I don't think there is much well-defined.)

By and large we have found performance on both sides not to be a problem,
occasionally you will of course want to use local storage for speed, but
not often as the difference is usually minor (remember, your local disk
is probably a slow winch while your remote disk is probably a much faster
winch, ethernet can usually run as fast as your local machine can handle
so you may often find remote disks to have better performance than local.)

Finally, there is TCP/IP for the 1108s which works well (they actually
do some remarkably clever things to fake network file system stuff, tho
you will still want PUP.)

	-Barry Shein, Boston University

P.S. Has anyone moved the PUP code to a SUN? I suspect it's just mostly
a nuisance chore (like byte-order stuff.)