Understanding the art of clustering

Do not be afraid to claim that clustering actually provides high availability in a given infrastructure. The aggregation of the capacity of two or more servers is meant to be a server cluster. This aggregation will be performed by means of the accumulation of several machines.

Do not get confused between scaling up, which is also called vertical scaling, and scaling down, which is also known as horizontal scaling. The horizontal scaling option refers to adding more commodity servers, unlike the vertical scaling option, which refers to adding more expensive and robust servers with more CPU and RAM.

This makes it imperative to differ between the terminologies of high availability, load balancing, and failing over, which will be detailed in Chapter 9, OpenStack HA and Failover.

Keep this in mind that for any of the previously mentioned terms, their configuration results always start from the clustering concept. You will discover how to differentiate between them in the next section.