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Introduction

CSCE455/855 Distributed Operating Systems. Introduction. Dr. Ying Lu ylu@cse.unl.edu. Giving credit where credit is due:. CSCE455/855 Distributed Operating Systems. Most of the lecture notes are from the textbook companion website

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Introduction

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  1. CSCE455/855Distributed Operating Systems Introduction Dr. Ying Lu ylu@cse.unl.edu

  2. Giving credit where credit is due: CSCE455/855Distributed Operating Systems • Most of the lecture notes are from the textbook companion website • Some of the lecture notes are based on slides created by Dr. Zahorjan at Univ. of Washington and Dr. Konev at Univ. of Liverpool • I have modified them and added new slides

  3. What is an Operating System? • The text: • “an intermediary between the user of a computer and the computer hardware” • “manages the computer hardware” • “an amazing aspect of operating systems is how varied they are in accomplishing these tasks … mainframe operating systems … personal computer operating systems … operating systems for handheld computers …”

  4. Applications OS Hardware What is an Operating System? • An operating system (OS) is: • a software layer to abstract away and manage details of hardware resources • a set of utilities to simplify application development

  5. Course Aims • Provide an understanding of the technical issues involved in the design of modern distributed (operating) systems • Appreciate the main principles underlying distributed systems: processes, communication, naming, synchronization, replication and consistency, fault tolerance, and security

  6. What is a distributed system?&What are the design goals?

  7. What is distribution transparency?

  8. Transparency in a Distributed System

  9. Openness in Distributed Systems • An open distributed system • Offers services according to standard rules that describe syntax and semantics of the services • Can interact with services from other open systems, irrespective of the underlying environment • Examples • In computer networks, standard rules govern the format, contents and meaning of messages sent and received • In distributed systems, services are specified through interface description language (IDL)

  10. So, what is Scalability?

  11. How to make a system scale?

  12. Centralized Solutions: Obstacles for Achieving Size Scalability Examples of scalability limitations.

  13. Characteristics of Decentralized Algorithms • No machine has complete information about the system state • Machines make decisions based only on local information • Failure of one machine does not ruin the algorithm • Three is no implicit assumption that a global clock exists

  14. Internet/World Wide Web

  15. Cloud Computing • A cloud is an elastic execution environment of resources providing a metered service at multiple granularities. • On-demand resource allocation: add and subtract processors, memory, storage.

  16. Amazon Web Services • Elastic Compute Cloud (EC2) • Rent computing resources by the hour • Basic unit of accounting = instance-hour • Additional costs for bandwidth • Simple Storage Service (S3) • Persistent storage • Charge by the GB/month • Additional costs for bandwidth • You’ll be using EC2 for a programming assignment!

  17. What are ACID properties? What do A, C, I, and D represent?

  18. intranet % % ISP % % backbone satellite link desktop computer: server: network link: 1.4 Internet Instructor’s Guide for Coulouris, Dollimore, Kindberg and Blair, Distributed Systems: Concepts and Design Edn. 5 © Pearson Education 2012

  19. 1.4.1 World-Wide-Web

  20. http://www.google.comlsearch?q=lyu www.google.com Browsers Web servers Internet www.uu.se http://www.uu.se/ www.w3c.org http://www.w3c.org/Protocols/Activity.html File system of Protocols www.w3c.org Activity.html 1.4.2 Web Servers and Web Browsers Instructor’s Guide for Coulouris, Dollimore, Kindberg and Blair, Distributed Systems: Concepts and Design Edn. 5 © Pearson Education 2012

  21. Announcement • To build our class roster • Send our TA Weiyue Xu (weiyue AT cse.unl.edu) an email with subject “CSCE455/855 roster”, your photo (<2MB) and your name by this Saturday

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