Scaling
Classification of scaling
Vertical (Scaling up/ down): Increase or decrease the resources allotted to a process
amount of memory
number of processor cores
storage available
Horizontal (Scaling out/ in): Run additional, parallel jobs on the system
You should track your cluster resource usage as a part of your maintenance procedures, and scale accordingly. This secures correct implementation. The essence of a cluster makes horizontal scaling simple. Your administrator can add or remove nodes as required. Here, consider the needed level of redundancy. If it is not met, your cluster's availability will suffer.