A grid is a computer network of geographically dispersed and heterogeneous computational resources as shown in Figure. Unlike cloud, whose primary focus is to provide services, a grid is more application specific and creates a sense of a virtual supercomputer with an enormous processing power and storage. The constituent resources are called nodes. These different nodes temporarily come together to solve a single large task and to reach a common goal.
Nowadays, countless computational nodes ranging from hand-held mobile devices to personal computers and workstations are connected to LAN or Internet. Therefore, it is economically feasible to reuse or utilise their resources like memory as well as processing power. The grid provides an opportunity to solve computationally intense scientific and research problems without actually procuring a costly hardware.
Grid can be of two types—
(i) Data grid, used to manage large and distributed data having required multi-user access, and
(ii) CPU or Processor grid, where processing is moved from one PC to another as needed or a large task is divided into subtasks and divided to various nodes for parallel processing.
Grid computing is different from IaaS cloud service. In case of IaaS cloud service, there is a service provider who rents the required infrastructure to the users. Whereas in grid computing, multiple computing nodes join together to solve a common computational problem.
To set up a grid, by connecting numerous nodes in terms of data as well as CPU, a middleware is required to implement the distributed processor architecture. It includes software for security, resource management, data management, communication, fault detection, etc.
