Class Note for CMPSCI 677at UMass(6)
Class Note for CMPSCI 677at UMass(6)
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This 12 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Massachusetts taught by a professor in Fall. Since its upload, it has received 25 views.
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Date Created: 02/06/15
Distributed Operating Systems Spring 2003 Pr ashan r Shenoy UMass Computer Science httplasscsumasseduNshenoycourses677 Momma m Course Syllabus CMPSCI 677 Dist buted Operating Systems Instructor Prashznt Shenoy 7 Email shenoy csumassedu Phone 413 577 0850 r Of cehours Tuesday 1230130 CS 336 or by appt T eachingAsst Gary Holness 7 Email gholnesscsumassedu Phone 413 545 3039 7 Of cehours TBA CS 311 413 5776310 Course web page httplasscsumasseduNshenoycourses677 Wampum ms Momma muss Course Outline Introduction today 7 What Why Why not 7 Basics Interprocess Communication 7 RPCs RMI message and streamoriented communication Processes and their scheduling 7 Threadprocess scheduling codeprocess migration Naming and location management 7 Entities addresses access points 05677 DismbutdeS Lenu21pag23 Mam muss Course Outline Canonical problems and solutions 7 Mutual exclusion leader election clock synchronization Resource sharing replication and consistency 7 DSM DFS consistency issues caching and replication Faulttolerance Security in distributed Systems Distributed middleware Advanced topics web multimedia realtime and mobile systems 05677 DismbutdeS LemxeLPAgeA Misc Course Details 0 Textbook Distributed Systems by Tannenbaum and Van Steen Prentice Hall 2001 0 Grading 7 45 Homeworks 20 34 programming assignments 35 7 l midterm and 1 nal 40 class participation 5 0 Course mailing list cs677 csumassedu 7 You need to add yourselfto this list see class web page Pre requisites 7 Undergrad course in operating systems 7 Good programming skills in a highlevel prog language M WW c5677 Mimics WW mm De nition of a Distributed System 0 A distributed system 7 Multiple connected CPUs working together 7 A collection of independent computers that appears to its users as a single coherent system 0 Examples parallel machines networked machines Wampum m Advantages and Disadvantages 0 Advantages 7 Communication and resource sharing possible 7 Economics 7 priceperformance ratio 7 Reliability scalability 7 Potential for incremental growth 0 Disadvantages 7 Distributionaware PLs OS5 and applications 7 Network connectivity essential 7 Security and privacy M MW c5677 mums WWW mm Transparency in a Distributed System Transparency Description Ac Hide differences in data representation and how a cess resource is accessed Location Hide where a resource is located Migration Hide thata resource may move to another location Relocation Hide Ithata resource may be moved to another location while n use Replication Hide thata resource may be shared by several competitive users Hide thata resource may be shared by several Concurrency competitive users Failure Hide the failure and recovery of a resource Persistence iri dzig hemer a sottware resource is in memory or Different forms of transparency in a distributed system Momma m Scalability Problems Concept Example Centralized services A single sewer for all users Centralized data A single online telephone book Centralized algorithms Doing routing based on complete information Examples of scalability limitations mamputer Science csa77 DismbuledOS Lecture 1 page 9 umss Hardware Concepts Multiprocessors 1 Multiprocessor dimensions 7 Memory could be shared or be private to each CPU 7 Interconnect could be shared busbased or switched A busbased multiprocessor CPU CPU CPU Memory Cache Cache Cache Bus p Computer39 Science csa77 DismbuledOS Learnerpage 10 um Multiprocessors 2 a A crossbar switch b An omega switching network Memories El E1 IE E CPUs Memories E J Pi Es 39 viii arms 3 I I 4 E m 5 ii Crosspoim switch 2gtlt2 switch a b Computer Science css77 Distributed 0s Lecture 1page 11 MASS Homogeneous Multicomputer Systems a Grid b Hypercube a b Computer Science css77 Distributed 0s Lecture 1 page 12 MASS Distributed Systems Models Minicomputer model eg early networks 7 Each user has local machine 7 Local processing but can fetch remote data les databases Workstation model e g Sprite 7 Processing can also migrate Clientserver Model e g V system world wide web 7 Userhas local Workstation 7 Powerful workstations serve as servers le print DB servers Processor pool model eg Amoeba Plan 9 r Terminals are Xterms or diskless terminals 7 Pool ofbackerrd processors handle processing M MW c5677 macros ml 3 mm Uniprocessor Operating Systems An OS acts as a resource manager or an arbitrator r Manages CPU IO devices memory OS provides a virtual interface that is easier to use than hardware Structure of uniprocessor operating systems 7 Monolithic eg MSDOS early UNIX 39 One large kernel that handles everything 7 Layered design 39 Functionality is decomposed intoN layers 39 Each layer uses services oflayer Nl and implements new services for layerN1 Momma macros mum 14 ms Uniprocessor Operating Systems Microkernel architecture Small kernel userlevel servers implement additional functionality No direct data exchange between modules E a OS Interface User Process File module U d application module Ser mo e A A 7 1 777777 7 7 7 V Kernel mode System call Microkernel Hardware m Computer Science C3677 Distributed os Lecture 1 page 15 quotMASS Distributed Operating System Manages resources in a distributed system 7 Seamlessly and transparently to the user Looks to the user like a centralized OS 7 But operates on multiple independent CPUs Provides transparency 7 Location migration concurrency replication Presents users with a Virtual uniprocessor m Computer Science C3677 Distributed os Lecture 1 page 16 UMASS Types of Distributed OSs sistem Description Main Goal DOS ghwcoupi ed ope39atmg wstem for ma Hide md manage processors and homogeneous multicomputers hardware resources NOS Loosdvrcoupied operating syatem for Offer ioca services hemrogeweous rruiucomputers LAN and WAN m remom chem Additional layer atop ofNOS impiemm ng generair Provide distribution Mdd w e purpose services iranspaem M MW cam mamas mam 7 am Multiprocessor Operating Systems 0 Like a uniprocessor operating system 0 Manages multiple CPUs transparently to the user 0 Each processor has its own hardware cache 7 Maintain consistency of cached data Momma amm taming a a Multicomputer Operating Systems Machine A Machine B Machine C l l l l Distributed applications Distributed operating system services Kernel Kernel Kernel Network l A Compurer Science C5677 Distributed os Lecture Lpage 19 um Network Operating System Machine A Machine B Machine C Distributed applications Network 08 Network 08 Network 08 services services services Kernel Kernel Kernel Network Computer Science C5677 Distributed os Lecture 1 page 20 mans Network Operating System 0 Employs a clientserver model 7 Minimal OS kernel 7 Additional functionality as user processes File server Client 1 Client 2 Q DiSkS 0n WhiCh shared file system Request Reply Q IS stored Network Computer Science C5677 Distributed os Lecture 1 page 21 man Middleware based Systems Machine A Machine B Machine C Genera i I Distributed applications Middlemre services Network Us Network OS Network OS servtoes Servle Services i Km i i Kama i i Kama Network miCompL 39er Science C5677 Distributed os Lecture 1 page 22 uMAss Comparison between Systems Dislributed os Mddl Item Network 05 b sedes gre Multiproc Mullicomp Degree of Dansparencv Ve39Y ngh ngh Low ngh Same as on 5 nodes Yes Yes No No Number of cones of as 1 N N N Shared Ems for comrmmcan on WWW Messages Fdes Mode specmc G oba G oba Resource management mm d smbuted Per node Per node Sca abwhty No Nbderatew Yes Ymes Opemese dosed dosed Open Open m empm 05677 News WWW muss
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