Capacity Planning

Capacity Planning is the determination of the overall size, performance and resilience of a computer or system. The detailed components of a Capacity Planning initiative will vary, depending upon the proposed usage of the system, but the following should always be considered :-

• the expected storage capacity of the system and the amount of data retrieved, created and stored within a given cycle.
• the number of on line processes and the estimated likely contention.
• the required performance and response required from both the system and the network i.e. the end to end performance.
• the level of resilience required and the and the planned cycle of usage - peaks, troughs and average.
• the impact of security measures e.g. encryption and decryption of all data.
• the need for 24x7 operations and the acceptability of downing the system for maintenance and other remedial work.

When capacity planning, the more information available about usage patterns and overall systems' loading, the better. Recently, with the exponential increase in Internet Web site usage, the results from any Capacity Planning have been, at best of limited use, and at worst, useless. The reason is because, it has been almost impossible to predict the possible volume of traffic (hence load) with the result that many sites have simply gone down under the excessive load conditions. Therefore, Capacity Planning needs to consider the real possibility of excess load scenarios and plan accordingly. (but there are no easy answers).