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)