Guy kolbis

There are several keywords that I use frequently when talking about architecture and software development. There are times that I feel that those whom I talk to do not really understand the meaning of those words. So, I decided to post the definitions for those keywords. This is definitely not a complete list, but it is a good starting position.

Scalability

Scalable computing involves using a computer system or software that can adapt to the need for more powerful computing capabilities.

In terms of software, scalability is the ability and flexibility of an application to meet growth requirements of an organization and continue to function well as it is changed in size or volume.

In terms of hardware, a scalable computer system may begin with one node, but more nodes can be added as and when there is a need for more computing capabilities.

Availability

The property of a system or a system resource that ensures it is accessible and usable upon demand by an authorized system user. With any IT system it is desirable that the system and its components (be they hardware or software) are up and running and fully functional for as long as possible, at their highest availability.

Redundancy

The ability of a system to keep functioning normally in the event of a component failure, by having backup components that perform duplicate functions.

Clusters

A computer cluster is a group of tightly coupled computers that work together closely so that in many respects they can be viewed as though they are a single computer. There are several categories for clusters:

• High-availability (HA) clusters - are implemented primarily for the purpose of improving the availability of services which the cluster provides.
• Load-balancing clusters - operate by having all workload come through one or more load-balancing front ends, which then distribute it to a collection of back end servers.
• High-performance computing (HPC) clusters - are implemented primarily to provide increased performance by splitting a computational task across many different nodes in the cluster, and are most commonly used in scientific computing.