QUESTIONS Distributed Computing Systems. Prof. Ananthanarayana V.S. Dept. Of Information Technology N.I.T.K., Surathkal

Size: px

Start display at page:

Download "QUESTIONS Distributed Computing Systems. Prof. Ananthanarayana V.S. Dept. Of Information Technology N.I.T.K., Surathkal"

Cecilia Mathews
5 years ago
Views:

1 QUESTIONS Distributed Computing Systems Prof. Ananthanarayana V.S. Dept. Of Information Technology N.I.T.K., Surathkal

2 Questions Fundamentals 1. Discuss five fundamental issues in distributed system 2. What are different transparencies which can be observed in distributed system? List basic transparencies need to be supported by the distributed system. 3. Give main two technical differences between Network OS and Distributed OS. 4. Consider a distributed environment with four systems, A,B,C and D. Name the type of transparencies required in each of the following situations: a. Data available at all four systems and user want to modify the data at D. b. Printer connected to A is disconnected and connected to B. User wants to access that printer. c. Breakdown of system, D. d. User want to access the software X without knowing its whereabouts. 5. Consider that railway reservation system is implemented using distributed environment. List out the possible types of transparencies need to be incorporated in this system. Justify your answer. 6. List any two situation which clearly shows the need for distributed coordination. How this can be achieved? 7. Explain two types of resource management in distributed system. 8. Give characteristics and goals of centralized OS, network OS, distributed OS and cooperative autonomous system.

3 Questions Distributed Coordination 1. What are causally related events? 2. Show that using single value for logical clock C, it is not possible to ensure that if C(a) < C(b), then a b, where denoted happenbefore relation among the events in a distributed system. 3. Give implementation rules of Lamport s logical clock and vector clock. In which type of applications vector clocks are more appropriate? 4. Why global clock is important in a distributed system? Why this is an issue? How this can be realized? 5. Consider a bank database which is fully replicated. Give an algorithm/protocol for ordering of transactions in above situations. 6. Differentiate implementation rules of Vector clock and Lamport s clock. 7. Prove that vector clock condition is strong. What is the significance of this condition?

4 Questions Ordering of Messages S p a c e e11 e12 e21 e22 Time e31 e32 1. Trace SES protocol to ensure the ordering of messages in above scenario. 2. Discuss BSS protocol for causal ordering of messages. In what way this algorithm is different from SES protocol?

5 Questions Global State Detection 1. Why global state detection is an issue in distributed system? 2. Give the consistent global state requirements in DCS. When the global state is said to be strongly consistent? 3. Let C be the channel from node S1 to S2. Show that a consistent global state must always satisfy n m, where n is the number of messages sent by S1 along C before S1 state is recorded and m is the number of messages received by S2 along C before S2 state is recorded. 4. Consider a DCS with set of sites, S={S1,S2,S3}. With respect to real time, t, the global state G={LS1, LS2,LS3} (where LSi is local state of site Si) is recorded. Let LS1={recv(e21, e11), send(e12, e31), recv(e22, e13)} Let LS2={send(e21, e11), send(e22, e13), recv(e14, e23)} Let LS3={recv(e12, e31), send(e32, e15), recv(e16, e33)} where eij is jth event at ith site; send/recv(x,y) send/receive message from x to y. Comment with justification on global state G recorded. 5. Differentiate: Transit less global state from Consistent global state

Questions Distributed Process Synchronization 1. In Raymond s tree based DME algorithm, what happens to the message overload when arrival rate of critical section requests increases at each node? 2.

If communication channel is NON FIFO, does a. Lamport s DME algorithm ensures mutual exclusion condition? b. Ricart Agrawala s permission based DME algorithm ensures mutual exclusion condition? 5.

6 Questions Distributed Process Synchronization 1. In Raymond s tree based DME algorithm, what happens to the message overload when arrival rate of critical section requests increases at each node? 2. How deadlock situation is handled in Meakawa s DME algorithm? 3. Compare the performance of Ricart Agrawala s token based DME algorithm with Ricart Agrawala s permission based algorithm 4. If communication channel is NON FIFO, does a. Lamport s DME algorithm ensures mutual exclusion condition? b. Ricart Agrawala s permission based DME algorithm ensures mutual exclusion condition? 5. Token based DME algorithms are less fault tolerant than permission based algorithms Comment on this. 6. Which one of the following algorithm is fair with respect to Lamport s clock? Why? 1. Meakawa s DME algorithm 2. Ricart Agrawala s DME algorithm 3. Raymond s tree based DME algorithm 7. Differentiate: 1. Fair DME algorithm from starvation free DME algorithm 2. Framework for DME algorithm from its centralized counterpart. 3. Permission based DME algorithm from token based DME algorithm 4. DME algorithm performance measure: Response time from Waiting time.

Questions Distributed Process Synchronization 8. Give pseudo code for 1. Lamport s DME algorithm 2. Ricart Agrawala s permission and token based DME algorithm 3. Meakawa s DME algorithm 4.

Meakawa s DME algorithm 4. Raymond s tree based DME algorithm 10. What is the necessity of INQUIRE and RELINQUISH message in Meakawa s DME algorithm? 11.

7 Questions Distributed Process Synchronization 8. Give pseudo code for 1. Lamport s DME algorithm 2. Ricart Agrawala s permission and token based DME algorithm 3. Meakawa s DME algorithm 4. Raymond s tree based DME algorithm 9. Compare the performance measures between following algorithm: 1. Lamport s DME algorithm 2. Ricart Agrawala s permission and token based DME algorithm 3. Meakawa s DME algorithm 4. Raymond s tree based DME algorithm 10. What is the necessity of INQUIRE and RELINQUISH message in Meakawa s DME algorithm? 11. What is the problem if the topology considered for Raymond s algorithm has a cycle? 12. How you can convert the following algorithm into greedy algorithms? 1. Ricart Agrawala s token based DME algorithm and 2. Raymond s tree based algorithm

Questions Inter Process Communication 1. What are the various message orderings that are used in group communication? 2. What are different failure handling semantics in RPC? 3.

8 Questions Inter Process Communication 1. What are the various message orderings that are used in group communication? 2. What are different failure handling semantics in RPC? 3. List various semantics of send primitives. Give appropriate application for each of the semantics 4. What is atomic broadcast protocol? Give general overview of its implementation. 5. Differentiate system call and local procedure call. 6. Discuss the system calls which are used to provide the communication 1. Between related processes 2. Between the processes within the file system 3. Between any arbitrary processes 7. How parameter and result passing is handled in RPC? 8. Give block schematic to explain how a single process can communicate with two of its child processes using pipes? What are the limitations of pipes? 9. Consider a client server application. Which semantics of send is preferred? Why?

Questions Inter Process Communication 10. Give block schematic which shows the various steps in RPC handling. 11. It is required to update a bank account in DCS in order.

9 Questions Inter Process Communication 10. Give block schematic which shows the various steps in RPC handling. 11. It is required to update a bank account in DCS in order. Which message ordering is appropriate? Why? 12. List the requirements of broadcast protocol. 13. What is indirect communication? Give an application where this type of communication is appropriate. 14. What are the roles of binding register in RPC? In order to load balance the service providers, what is the requirements of binding register 15. What are pros and cons of different types of binding? 16. What do you mean by non blocking RPC? Give an example. 17. Differentiate unanimity and uniformity requirements of broadcast protocol.

10 Questions Distributed Deadlocks 1. Differentiate reusable and consumable resources with example. 2. What are different resource request models? 3. Which types of deadlocks are handled by wait for graph (WFG)? 4. Which types of deadlocks are not handled by WFG? How this can be handled? 5. Show that how wait die / wound wait protocol ensures prevention of deadlocks? 6. How wait die / wound wait protocol can be extended to handle deadlock prevention in more than one process waiting scenarios? 7. What do you mean by false deadlocks in distributed environment? How this can be detected?

11 Questions Distributed Deadlocks 8. Consider Chand Misra Haas distributed deadlock detection and recovery algorithm. How an unique victim is identified if resource request model is (a) single unit (b) AND resource request model? 9. Which is the deadlock prevention method where there is no resource pre emption? Why? 10. Explain the situation where in a cycle in WFG does not implies the deadlock. How the deadlock can be detected in such situations? 11. Consider an OR resource request model and WFG, G = {V,E}, where V = {P1, P2, P3} and E = {<P1, P2>, <P2, P3>, <P3, P1>}. Is the system in deadlock state? Justify.

12 Questions Load Balancing 1. Differentiate CPU scheduling from Job scheduling. 2. Differentiate Job scheduling with load balancing. 3. What are the objectives of load balancing? 4. Why and what knowledge about the node is important in load balancing? What are the issues if knowledge estimated is not correct? 5. What is the advantage of sender initiated algorithm over receiver initiated algorithm? 6. Compare transfer and location policy between sender initiated and receiver initiated algorithm 7. What are the characteristics of above average algorithm? 8. How the system load is estimated in above average algorithm?

13 Questions Load Balancing 9. What are the drawbacks of above average algorithm when compared with stable symmetrically initiated algorithm? 10. What is learning process in stable symmetrically initiated algorithm? 11. Explain location policy of stable symmetrically initiated algorithm. 12. What is the advantage of stable sender initiated algorithm over stable symmetrically initiated algorithm? 13. What is the use of status vector in stable sender initiated algorithm? 14. What are the performance parameters for a load balancing algorithm?

Distributed Deadlocks. Prof. Ananthanarayana V.S. Dept. of Information Technology N.I.T.K., Surathkal

Distributed Deadlocks. Prof. Ananthanarayana V.S. Dept. of Information Technology N.I.T.K., Surathkal Distributed Deadlocks Prof. Ananthanarayana V.S. Dept. of Information Technology N.I.T.K., Surathkal Objectives of This Module In this module different kind of resources, different kind of resource request