DS notes #2

dated- 18-1-2017

• Distributed Computing model

Classifications

1. Mini computer model
2. Workstation model
3. Workstation server model
4. Processor pool model
5. Hybrid model

1. Mini computer model

• Extension - centralised time - sharing system.
• Remote access - other microcomputers.
• Network - allows access remote resources.
• Example - early ARPANET.

2) Workstation model

• Idle workstation - process jobs other workstation.
• Not simple to implement.
• 
  

Issues

• Idle workstation.
• Process transferred
• Example- sprite system and xerox PARC.

3) Workstation server model

4)Processor pool model

• Run server - manages and allocates processor.
• Example- ameoba, plan g and cambridge DCS.

5) Hybrid model

• combines - workstation - server and processor pool model.

• Advantages of distributed systems

1. Information sharing among geographically distributed users.
2. Resource sharing
3. Better price - performing ratio
4. Higher reliability and availability against component failures.

             Reliability - multiple copies of data.

             Availablity - redundancy.

     5) Starter response time and higher through put.

     6) extensibility

     7) Better flexibility.