Grid computing is an evolutionary technology that borrowed features from technologies including distributed computing, web services, Internet and cryptography technologies. This is to provide computational resources for some specific tasks. And this technology achieves high throughput computing.

What is grid?

A grid is an aggregated system consisting of sparsely located computing devices, storage devices, instrumentation devices and control devices built a top internetworks. So, basically a grid is a collection of computers working to solve a particular problem and exhibit good performance. It is flexible, transparent, secure, coordinated resource sharing among dynamic collection of users, institutions and resources.

The grid systems aim to allow donors to offer resources for a given grid and allow any user to

claim resources dynamically in order to perform computational or data intensive task.

Virtualization

Virtualization here means integraion of geographically distributed and heterogeneous systems. Virtualization in grid allows users to use services in a transparent manner. Users need not worry about location of computing resources. When the user submits service request at the entry node, grid system locates the computing resources that can serve the request.

There are two types of grids: Service Grids and Desktop Grids.

Service Grids

A resource can be added to the service grid by installing a predefined software set or middleware. As the middleware is very complex it is difficult to maintain it. So service grids are mostly used in large institutions where experts take care of the infrastructure and ensure availability of the grid.

Desktop Grids

Desktop Grids (DG) depend on general public to donate resources. So they are widely known as volunteer computing or public resource computing. These are based on simple architecture. Volunteer computing is able to integrate dispersed heterogeneous resources with much ease.

Advantage:

• Any one can easily add his resource as installation of software is easy.

Disadvantages

• Desktop grids cannot be uses as services.
• One cannot use the grid if he has not already set his project to function in this environment.
• Participants cannot use DG for their own goals.
• Only a limited community can use DG resources due to the above limitations.