The cluster-stats API provides similar output to the node-stats. There is one crucial difference: Node Stats shows you statistics per node, while cluster-stats shows you the sum total of all nodes in a single metric.

This provides some useful stats to glance at. You can see for example, that your entire cluster is using 50% of the available heap or that filter cache is not evicting heavily. Its main use is to provide a quick summary that is more extensive than the cluster-health, but less detailed than node-stats. It is also useful for clusters that are very large, which makes node-stats output difficult to read.

The API may be invoked as follows:

GET _cluster/stats