Computing Resource Paradigms
CS3353
Computing Resource Paradigms
• Centralized Computing
• Distributed Computing
Early Centralized Computing Paradigm
• Characterized by one central computer.
• Housed in a limited access, climate controlled room.
• A shared resource – users connect through dumb-terminals.
• Limited interactive access.
• Jobs are submitted through batch job-queues.
Centralized Computing
• There remain highly specialized computer systems of this type:
• Supercomputers designed for special resource intensive problem solving.
Cray T3E/512-PE Supercomputer Mainframe
Centralized Computing Advantages
• Ideal for maintaining a high level of security.
• Climate controlled environment is equipment friendly.
• Reduces maintenance costs.
Distributed Paradigm
• Demand driven by departments wanting access to more computing resources beyond the confines of centrally controlled systems.
• Unix becomes a popular operating system for this paradigm.
• HP, Sun, SGI, and others ride this wave during the 1980’s.
DEC Micro-VAX
Client-Server
• The spread of networks and low cost network hardware led to the client-server computing paradigm. This successfully merges the two central and distributed paradigms.
• Computers are interconnected by a network.
• The computers are classified as either clients or servers in the network.
Server
• A powerful computer configured to provide services to other computers within a computing system environment.
• Example Services:– Disk– Printer– Application– E-mail– etc
Server
• The server is typically a powerful computer configured with:
• Fast processors (1 or more)
• Fast and reliable disk storage
• Memory rich
Server
• Central location for the server allows ease of maintenance and high levels of security.
• Simplifying the maintenance of the system helps control costs.
• Small operations (businesses) can put a powerful central computing system in a small room. There it can be relatively secure and easy to maintain.
Server Rack
Behind the Server Rack
The Client
• A client is configured to access specific services within the boundary of the defined computing system environment.
• Client classifications:– Fat client: fully functional workstation– Thin client: a dumb terminal or graphical
display– Hybrid client: between thin and fat.
Client
• Fat clients are fully functional computers with local storage and computing capability.
• Thin clients rely on a server to provide storage and computing resources. Characterized as diskless and without a processor.
• Hybrid clients provide some computing resources independent of a server; storage is provided by a server.
Client
• Thin/Hybrid clients can cost less than fat-clients to purchase and maintain when carefully chosen.
• Work well for:– public access areas– high security environments– When full function workstations are unnecessary.– Reduces maintenance for cost conscious businesses.
$300 client