[ih] Distributed file systems [was: As Flag Day approaches at CMU]

Sat Sep 20 06:11:57 PDT 2025

I know bits of Rick's work as his team worked on the same hallway as my
office when I first got to BBN.  This is all from memory and may have gaps
errors.  I do see some documentation is online:
https://apps.dtic.mil/sti/tr/pdf/ADA199891.pdf

In the early 1980s Rick had a substantial team working to develop an
object-oriented distributed system called Cronus.  This is just a few years
after Smalltalk-80 came out and Cronus had a very
Smalltalk-over-the-network feel to it.

Initially, Cronus was peer-to-peer.  Each object needed to know where on
the network any object it wanted to talk to was.  Which was fine initially
and allowed the Cronus team to work out many many issues in generic
object-to-object communication and encapsulation (Cronus sought to sit over
all existing operating systems -- which meant you had nasty problems of
"what is a file object?" when there were different file systems).  But by
the time I arrived on the hallway in 1983, Cronus was bumping into problems
of scaling because locating objects was painful (which connects back to
Satya's note).

Then Mike Dean, fresh out of grad school, joined the Cronus project in (if
memory is right) 1984.  After a few months of learning Cronus, Mike
realized that a level of indirection that allowed objects to discover each
other was needed and, again if memory serves, over a weekend wrote an
object broker whose job was to match up objects that wanted to talk.  (If
he didn't do it over a weekend, he could have -- Mike, as a programmer, was
extraordinary).  And Cronus, as a research project took off, as it now had
the key components -- object communication and object broker -- to realize
Rick's vision.

Rick and Mike collaborated closely for the next few years and I think it
had a key role in both their careers.  Rick went on to do valuable work in
middleware and how to interconnect systems (by which I mean layer 6/7
things).  Mike went on to be a force in information discovery, especially
his work on ontologies in the world wide web.  Alas both have passed away
(far too early).

Craig

On Fri, Sep 19, 2025 at 3:52 PM Barbara Denny via Internet-history <
internet-history at elists.isoc.org> wrote:

>
>
> The name Rick Schantz popped up in my head.  He was doing some work in
> this area in the 70s and later?  Here are a couple links that might lead
> you to more info if you can get them. I don't have ready access to the IBM
> one. It mentions distributed file systems in the abstract.
> https://research.ibm.com/publications/interprocess-communication-systems
>
>
> https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://eecs.wsu.edu/~cs565/Papers/Schantz-DistSysBBN1970-1995.pdf&ved=2ahUKEwjZ-Z245uWPAxU3EEQIHYYiN2IQFnoECCEQAQ&usg=AOvVaw1qfpTTB6K2dytZx3kBry29
> The reference above is a chapter on distributed computing at BBN.
> I am very sad to have to report that he also has passed away.  It is
> getting difficult to search for people .
> https://schlossbergchapel.com/obituary/richard-schantz/
> barbara
>
>     On Wednesday, September 10, 2025 at 09:27:23 PM PDT, Brian E Carpenter
> <brian.e.carpenter at gmail.com> wrote:
>
>  Hi Barbara,
>
> That makes total sense, and I doubt if Brian Randell would be surprised.
> I've put him in Bcc in case he wants to comment.
>
> The Named Data Networking project is still tackling this space:
> https://named-data.net/project/execsummary/
>
> Regards/Ngā mihi
>     Brian Carpenter
>
> On 11-Sep-25 15:41, Barbara Denny via Internet-history wrote:
> >  I was curious about the potential influence of the Unix United paper on
> work at CMU so I decided to just ask Satya. In my message to him, I
> included the part starting with  the sentence "AFS in particular *must*
> .."  and the 2 examples that follow from Brian's email.
> > I did tell him I wanted to post his answer to this list and he hasn't
> said no so ...
> > Excuse my trimming of the thread.  I seem to have problems posting to
> the list, especially when the body of the message is long.
> >
> > barbara
> >
> > ----- Forwarded Message -----From: Mahadev Satyanarayanan <
> satya at cs.cmu.edu>To: Barbara Denny <b_a_denny at yahoo.com>Sent: Monday,
> September 8, 2025 at 01:45:16 PM PDTSubject: Re: AFS question
> > Hi Barbara,
> > The Unix United paper (aka "Newcastle Connection") was published in
> > 1982.  We were indeed aware of that work by mid-1983, when serious
> > work on what eventually led to AFS began.  The name "Andrew" for the
> > whole project did not emerge until late 1985.  In fact, the first
> > published paper on AFS did not even use the name "AFS".  It referred
> > to the system as "The ITC Distributed File System" and the server
> > and client components as "Vice" and "Virtue" respectively.
> > Here is that very first AFS paper, from 1985:
> >      https://dl.acm.org/doi/10.1145/323647.323633
> >
> > Alas, the influence of Unix United on AFS was quite the opposite of
> > what the person who spoke with you thinks.  We actively worked hard to
> > AVOID an aspect of Unix United that we thought was totally wrong.
> >  From the beginning we believed that AFS needed to have Location
> > Transparency.  i.e. you could not tell where a file was located by
> > just looking at its pathname.  You had to ask the system to tell you,
> > and that location could change over time.  The 1985 paper explicitly
> > contrasts AFS with the design of Unix United.  If you look at
> > Section 6.1 in the above paper, it says this:
> >>
> >> Location transparency is a key issue in this context. In Locus,
> >> Vice-Virtue, Apollo and Roe it is not possible to deduce the
> >> location of a file by examing its name. In contrast, the Cedar File
> >> System and the Newcastle Connection embed storage site information
> >> in pathnames.
> >>
> >
> > Location transparency was identified as a non-negotiable requirement
> > of AFS since the very earliest conception of its design.  See, for
> > example, this September 1983 design document:
> >    http://reports-archive.adm.cs.cmu.edu/anon/itc/CMU-ITC-008.pdf
> >
> > BTW, there is a whole treasure trove of very early (1983-1985) design
> > documents from the ITC (Andrew project) at
> >    http://reports-archive.adm.cs.cmu.edu/itc85.html
> > Many things evolved over time, of course, but these early documents
> > capture the state of thinking at the time they were written.
> >
> > So the answer to your colleague is "Yes, Unix United was a big
> > influence on AFS, but in a totally negative way".  You may wish
> > to soften the blow in how you present it to him/her :-)
> >
> > Cheers
> >                --- Satya
> >
> > On Saturday, September 6, 2025 at 06:55:51 PM PDT,
> >
> >   Brian E Carpenter via Internet-history <
> internet-history at elists.isoc.org> wrote:
> >
> > "MIT wasn't the only place where the IMP became the de facto local area
> net."
> >
> > Which reminded me of Scrapbook at NPL. It was an early hyperlinked
> system but was also a (small scale) distributed file system by the mid
> 1970s. It was not widely known and is badly documented.
> >
> > I happened to meet and interview one of the Scrapbook team last year:
> >
> https://www.cs.auckland.ac.nz/research/groups/CDMTCS/researchreports/download.php?selected-id=884
> >
> > The Andrew File System and its descendants, like NFS, only came along in
> the 1980s. AFS in particular *must* have been influenced by the Unix United
> paper, which had examples like:
> >
> > cd /../unix2/user/brian
> > quicksort a > /../unix1/user/brian/b
> >
> > (where unix1 and unix2 were host names, and brian wasn't me, it was
> Brian Randell.)
> >
> > Regards/Ngā mihi
> >      Brian Carpenter
>
>
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