Dionicio D. Gante, Genevev G. Dionicio D. Gante, Genevev G. Reyes & Vanylive T. GalimaReyes & Vanylive T. Galima

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DistributeDistributed d Operating Operating SystemsSystems

What is Distributed What is Distributed Systems?Systems?

Consists of several computers that do not share a memory or a clock;

The computers communicate with each other by exchanging messages over a communication network; and

Each computer has its own memory and runs its own operating system.

Distributed System is used to describe a system with the following characteristics:

Architecture of Distributed OS

What is Distributed What is Distributed Operating Systems?Operating Systems?

Definition of Distributed OSIt extends the concepts of resource management and user friendly interface for shared memory computers a step further, encompassing a distributed computing system consisting of several autonomous computers connected by a communicating network.

Issues in Distributed OS Global Knowledge Naming Scalability Compatibility Process Synchronization Resource Management Security Structuring

What are the Advantages What are the Advantages of Distributed Systems of Distributed Systems Over Traditional Time-Over Traditional Time-

Sharing Systems?Sharing Systems?

The Main Advantage of Distributed Systems is: They have a decisive price/

performance advantage over more traditional time-sharing systems

Other Significant Advantages: Resource Sharing Enhanced Performance Improved Reliability and availability Modular expandability

What are the three What are the three categories of a categories of a

distributed systems?distributed systems?

Tanenbaum and Renesse classified distributed systems into three broad categories, namely: the minicomputer model, the workstation model and the processor pool model.

Minicomputer Model Workstation Model Processor Pool Model

Categories of Distributed Systems

What is mutual What is mutual exclusion?exclusion?

Mutual exclusion is a collection of techniques for sharing resources so that different uses do not conflict and cause unwanted interactions.

What are the differences What are the differences between mutual between mutual

exclusion in a single exclusion in a single computer systems from computer systems from

distributed systems?distributed systems?

What is the primary What is the primary objective of mutual objective of mutual

exclusion?exclusion?

To maintain mutual exclusion; that is, to guarantee that only one request accesses the critical section at a time.

What are the What are the characteristics important characteristics important

in mutual exclusion?in mutual exclusion?

Characteristics are considered Characteristics are considered important in a mutual exclusion important in a mutual exclusion algorithm:algorithm: Freedom from Deadlocks Freedom from Starvation Fairness Fault Tolerance

How to measure the performance The number of messages necessary

per CS invocation. The synchronization delay The response time

Thank you for listening Thank you for listening and for not asking and for not asking

questions!questions!