This document discusses different distributed computing system (DCS) models: 1. The minicomputer model consists of a few minicomputers with remote access allowing resource sharing. 2. The workstation model consists of independent workstations scattered throughout a building where users log onto their home workstation. 3. The workstation-server model includes minicomputers, diskless and diskful workstations, and centralized services like databases and printing. It provides an overview of the key characteristics and advantages of different DCS models.

1. VMV COMMERCE, JMT ARTS & JJP SCIENCE
COLLEGE
(Institute of Computer Studies and Research)
Wardhaman Nagar, Nagpur-08
Created By:Harshad D. Umredkar
MCA-II (Sem-II)
2013-14
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2. Introduction
DCS
Models
Conclusion
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3. 

Processors->Communication Network->Local
memory/Peripherals
Resources: Local
 Remote
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4. 




Minicomputer Model
Workstation Model
Workstation Server Model
Processor Pool Model
Hybrid Model
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5. 

Extension of the centralized time sharing
system.
few minicomputers

Remote access to other minicomputers.

resource sharing with remote users is desired.
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6. The distributed system based on minicomputer model
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7. 



Consists of several workstations.
The workstations are independent computers with
memory, hard disks, keyboard and console.
A company's office or a university department may have
several workstations scattered throughout a building or
compass.
User logs onto one of the workstations called his or her
home workstation
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8. A distributed system based on the workstation model
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9. This model is not so simple to implement because
several issues must be resolved. These issues are
as follows:
Idle workstation
How is a process transferred from one workstation to
get it executed on another workstation
a workstation that was idle until now and was being
used
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10. 
few minicomputers and several workstations
interconnected
◦ Diskfull Workstation
◦ Diskless Workstation

types of services, such as database service and print service
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11. Fig 3: A Distributed System based on the workstation-server model
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12. 


Cheaper
Diskless workstations are also preferred to dishful
workstations from a system maintenance point of view.
Users have the flexibility to use any workstation

The request-response protocol

Guaranteed response time .
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13. 



large number of microcomputer and minicomputers
based on the observation that most of the time a user does
not need any computing power
A user submits a Job for computations are temporarily assigned
to the job by the run server
the entire processing power is available for use by the
currently logged-users
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14. Figure 4: A distributed computing system based on processor-poor model
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15. 
Based on the workstation-server model but with the
addition of a pool of processors.

Requires several computers concurrently for efficient
execution.

Gives guaranteed response to interactive jobs by
allowing them to be processed on local workstations
of the users.

Process allocated dynamically for the computations.

More expensive.
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16. 


The concept of distributed computing is the most
efficient way to achieve the optimization.
It deals with systems(hardware and software) , that
contain more than one processing / storage and
run in concurrently.
Main motivation factor is resource sharing.
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