Computer cluster usage. Graph showing computer cluster usage (horizontal axis) over time (vertical axis). Time is measured in hours (top is zero), each subunit is 15 minutes and each column represents one cluster node. A computer cluster is a group of computers (nodes) linked closely together to form a network. The collective power of a cluster provides improved computing performance. This graph was created using Clusterpunch software which measures benchmarks across a computer cluster. The benchmarks report to users nodes that are less busy and therefore available to run memory intense applications.