UNIVERSITY OF HOUSTON
               Department of Computer Science

                COSC 6360: OPERATING SYSTEMS
        FINAL EXAMINATION AND QUALIFYING EXAMINATION
                     General Questions

                        May 13, 1993

CLOSED BOOK: You may have with you two sheets of notes.

1.   Consider  the  effect  of  the  availability   of   low
     bandwidth  links for portable computers.  How would the
     file system be managed?  Surely the Coda model  is  not
     the  only  possible  model.  Suppose you had a portable
     computer with 200 MB of disk, and a 64  kilobits/second
     link  that functioned "most of the time." How would you
     design the file system?  (20 points)

2.   Workstation are now  build  around  faster  and  faster
     CPU's.   As  a  result,  distributing a big computation
     over a  network  of  workstation  is  becoming  a  very
     attractive proposition.  What are the major limitations
     of the approach? (8 points) Can  networks  of  worksta-
     tions  execute efficiently all kinds of parallel compu-
     tations? (6 points) What can we expect from future net-
     works of workstations (8 points)

                   UNIVERSITY OF HOUSTON
               Department of Computer Science

                COSC 6360: OPERATING SYSTEMS
                     FINAL EXAMINATION
                   Questions on Readings

                        May 13, 1993

CLOSED BOOK: You may have with you two sheets of notes.

1.   Compare the advantages and disadvantages  of  symmetric
     and asymmetric cryptosystems. (10 points)

     THIS QUESTION WAS RELATED TO A PAPER THAT IS NOT ANYMORE IN THE
     READING LIST.  IT WILL BE NOT BE ASKED AGAIN.

2.   How does L. Lamport defines the "happened before" rela-
     tion? (10 points)

3.   What objects are stored in Amoeba's directory server  ?
     (3 points) How are they stored? (7 points)

4.   Describe the mechanism used by  Sprite  to  locate  the
     file server storing a specific file. (10 points)

5.   What is  the  role  of  segments  in  the  Sprite  log-
     structured file system?  (10 points)

6.   What  are  the  advantages  and  disadvantages  of  the
     optimistic   replication  scheme  used  in  Coda?   (10
     points)