ast@cs.vu.nl (Andy Tanenbaum) (03/13/91)
In article <kbrDM6m00hsQIl8Fhf@cs.cmu.edu> Rick.Rashid@cs.cmu.edu writes: >I recently met Andy (in Japan of all places) and I must say that I liked him >a lot. I also recommend the ameoba book he is advertising (I have used some >of the papers republished in the book in classes that I teach). > >That having been said, I have no idea why Andy insists on referring to >Mach as a Unix replacement and characterizing Ameoba as a "research system". ------ ?????? Whoa. Funny thing. I also met Rick Rashid in Japan. Nice guy too. Very good businessman as well as being an academic. Although I don't have a degree in software paleontology, by piecing together some of the clues, I get the following picture: - 21 March 1990: I post an announcement for a book full of Amoeba papers - 22 March 1990: I get >1000 requests for said book - 23 March 1990: I decide making the papers FTP-able would be a great idea - 16 Jan. 1991: I meet Rick Rashid at the Tokyo Prince Hotel - 11 March 1991: Rogue machine somewhere in the world reposts my message - 12 March 1991: Rick complains that I keep dumping on Mach - 13 March 1991: I try to figure out what is going on Anyway, other than one off-hand remark in my posting in March 1990, I haven't even mentioned Mach in netnews, and that one time, I even spelled the name right. Thus it isn't like I am going around INSISTING that Mach is this or that. I hardly talk about Mach at all. I have enough other stuff to do. Nevertheless, sometimes people (privately) ask me to characterize the difference between Amoeba and Mach. What I usually say is that Amoeba was designed from scratch as a transparent distributed system, and Mach was not. To my way of thinking, a transparent distributed system can be characterized as one in which when a user types ls -l (however you spell that) he or she can't tell WHERE the files are. Different files in the same directory may be on different machines or even in different countries. Location does not matter. Furthermore, when a process is run, the SYSTEM, and not the USER, decides which processor or processors to use. The user has no idea of where his or her programs run, and each successive command may well run on a different machine, depending on the global load on the system at the time. To the user, the whole collection of dozens or hundreds of machines is just one big computer. It's like the old CDC 6600. Even though there was 1 CPU and 10 PPUs, users thought of it as a single computer. That is what TRANSPARENT means. However, the 6600 was not distributed. To the best of my knowledge, Amoeba is a transparent distributed system and Mach is not. That's about all I really insist on. That Mach emulates 4.3 BSD in binary and Amoeba does not is indisputable, and I have never suggested otherwise. As to Mach being a UNIX replacement, I refer the reader to the OSF sales literature. I hope this clarifies what happened and my position. No hard feelings. Now we have to track down the rogue computer and sue it for malpractice. Andy Tanenbaum (ast@cs.vu.nl) ================= NOTE ABOUT GETTING AMOEBA PAPERS BY FTP ================ The Amoeba book consists of a collection of reprints of published papers. The papers can be gotten by FTP from machines in the U.S. and Europe: Site Name Internet address Directory ---- ---- ---------------- --------- VU ftp.cs.vu.nl 192.31.231.42 pub/amoeba UCSC midgard.ucsc.edu 128.114.14.6 pub/amoeba In addition to the papers, hundreds of pages of user manuals are also online. See the READ_ME file for details. Please FTP outside business hours to reduce the loads on our machines. The VU is on Amsterdam time (6 hours ahead of EST); UCSC is on PST. If you don't have FTP and still want a book, you can buy it from ACE, a Dutch company which is now commercially selling and supporting Amoeba. Their address is amoeba@ace.nl. After shipping 1000 free copies of a 300-page book last year, I have learned my lesson :-( Amoeba will be available for beta-testing shortly. I will post an announcement to the net when the time comes. Don't call me. I'll call you.