Problem:

(a) Discuss Distributed File System Caching.

(Your discussion should include the goal and architecture of distributed file system caching and the various possible caching locations together with their corresponding advantages and disadvantages).

(b) (i) In relation to Lamport's logical clock discuss:

? Happened Before Relation.
? Concurrent event.

(ii) Discuss how the Happen Before Relation is implemented using timestamps.

(c) (i) Briefly describe Christian's and Berkeley's physical clock synchronisation algorithms.

(ii) Are externally synchronised clocks also internally synchronised? What about the converse? Explain your answers