From time to time (several times a day) I can observe high traffic (100Mbps or more) lasting a few minutes between different pairs of nodes in cluster (ES 1.7.x) while there are no any ongoing replicas / relocation. For sure it's between nodes in clusters - I checked it on iftop. Any idea how to debug it? Standard log with INFO level doesn't show anything, enabling DEBUG shows too much info so I can't pinpoint culprit.
Kind regards -