by, naga manojna chintapalli. [email protected] chapter 2.2 transparency
TRANSCRIPT
OVERVIEW
• Evolution of Modern Operating systems
• Distributed Operating System
• Goals of DOS
• Definition of Transparency
• Types of transparency and their categorizations
• Distributed System issues & Transparencies
• DOS projects
• References
EVOLUTION OF MODERN OPERATING SYSTEMS
• 1st Generation: Centralized Operating System
• 2nd Generation: Network Operating System
• 3rd Generation: Distributed Operating System
• 4th Generation: Cooperative autonomous System
DISTRIBUTED OPERATING SYSTEM
• A collection of independent computers that appear to the system users as a single computer presenting a transparent view of a multiple computer system with distributed resources and control.
GOALS OF DOS
• Efficiency• Flexibility • Consistency• Robustness
TRANSPARENCY
• “Is defined as the concealment from the user and the application programmer of the separation of components in a DS, so that the system is perceived as a whole rather than as a collection of independent components”
TRANSPARENCY (CONTD.,)
• Goal motivated by the desire to hide all irrelevant system-dependent details from the user, whenever possible.
• It is more important in distributed systems due to higher implementation complexities.
• Shielding the system-dependent information from the users is a trade-o between simplicity ffand e ectiveness.ff
TYPES OF TRANSPARENCY
• We have 10 types of transparencies. Let us see them in detail.
ACCESS TRANSPARENCY
• Access transparency - accessing both local and remote system objects in a uniform way.
LOCATION TRANSPARENCY
• Location transparency - no awareness of object locations. Sometimes called name transparency.
• Users of a Distributed System are not aware where a resource is physically located.
• The resources are referred by logical names.
• Example: area codes
MIGRATION TRANSPARENCY
• Migration transparency - ability to move an object to a di erent location without changing its name; also ffcalled location independence.
CONCURRENCY TRANSPARENCY
• Concurrency transparency - allow the sharing of objects without interference.
• Multiple users sharing a resource without any interference.
• It is similar to the time sharing concept.
REPLICATION TRANSPARENCY
• Replication transparency - consistency of multiple instances (or partitioning) of files and data
PARALLELISM TRANSPARENCY
• Parallelism transparency - parallel activities without users knowing how, when and where they are taking place.
FAILURE TRANSPARENCY
• Failure transparency - fault tolerance.
• Despite any failures in the system the task needs to be completed successfully i.e., it ensures graceful performance and minimum damages to the user.
PERFORMANCE TRANSPARENCY
• Performance transparency - attempts to achieve a consistent and predictable performance level even with changes of the system structure or load distribution.
SIZE TRANSPARENCY
• Size transparency - modularity and scalability.
• The system can expand in size without the knowledge of the user. It pertains to the incremental growth of the hardware.
REVISION TRANSPARENCY
• Revision transparency - vertical growth of the system
• This transparency refers to the software revisions which are not visible to the users.
CATEGORIZATION OF TRANSPARENCIES
• Transparencies can be categorized based on the goals of the distributed operating systems.
Concurrency TransparencyParallelism Transparency
Performance Transparency
Efficiency
Failure TransparencyReplication Transparency
Size TransparencyRevision Transparency
Robustness
Access TransparencyLocation TransparencyMigration Transparency
Size Transparency Revision Transparency
Flexibility
Access TransparencyReplication Transparency
Performance Transparency
Consistency
DISTRIBUTED SYSTEM ISSUES & TRANSPARENCIES
PROJECTS
Example of projects based on distributed operating systems is
• E1
E1 is a distributed operating system project, based on the following concepts:
• object replication
• component model support
• Persistence
It Provides efficient access to the resources of computer network, implements a convenient programming model, isolating software developers from the intrinsic complexity of asynchronous distributed environment.
http://www.cs.utah.edu/~aburtsev/doc/e1_nicta_talk.pdf refer the link to know more about this project.
REFERENCES
[1] A. S. Tanenbaum, “Distributed Operating Systems”, Prentice Hall, pp.22-
25,2001.
[2] Y. Lu, “Distributed Operating Systems”, UNL.
[3 ]R. Chow, T. Johnson, “Distributed Operating Systems & Algorithms”, Addison
Weley, pp.29-32,1999.
[4] B. Karp, “RPC & Transparency”,UCL Computer Science,2006.
[5] Parallel and Distributed Operating System Group, MIT http://project-iris.net/
[6] IRIS: Infrastructure for Resilient Internet Systems http://project-iris.net/
[7] http://en.wikipedia.org/wiki/Transparency_(Distributed Systems)
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