Software Concepts in DS

Posted By on March 21, 2016


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Distributed Computing Models
Design Issue in DS

Distributed Operating Systems

  • Act as resource managers for the hardware while attempting to hide intricacies and the heterogeneous nature of the underlying hardware
  • Look to the user like a centralized OS – But operates on multiple independent CPUs
  • Provide transparency – Location, migration, concurrency, replication,…
  • Present users with a virtual uniprocessor

Types of Distributed Operating Systems

  • Tightly Coupled Systems: The OS tries to maintain a single global view of the resources it manages
  • Loosely Coupled Systems: A collection of computers, each running its own OS. Each OS cooperates in order to make their own services and resources available to the others

types of dos

 

DOS – Multiprocessor Operating Systems

  • Like a uniprocessor operating system
  • Manage multiple CPUs transparently to the user
  • Each processor has its own hardware cache
    • Maintain consistency of cached data
  • Communication through shared Memory
    • The OS must provide mechanisms to protect data against simultaneous access (Semaphors, Monitors, etc.)
  • Each computer has its own Kernel to manage local resources
  • Communication through message passing, or
  • Distributed shared memory (virtual shared memory)

multi os

 

Network Operating Systems

network os

  • Employ a client-server model

clientserver in network os

Pros:

  • Minimal OS kernel
  • Easy to add new machines to the system (usually all is needed is to connect the machine and make it known to the network)

Cons:

  • Lack transparency
  • Are more vulnerable to attacks
Distributed Computing Models
Design Issue in DS

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