The hub is constantly crashing. Hub is restarting every few minutes. It had been running fine for several weeks.
hub.log showed repeated entries of this message:
Decommissioning: Key length: 33 and file length: 134
and heartbeat failures for multiple robots.
niscache on the Secondary hub contained 122,000 files (only 17 MB) but for some reason was causing the hub to continuously restart.
Note that snmpcollector is installed on this secondary hub.
Then the secondary hub robot was successfully listening on port 48000 and the hub stopped restarting.
niscache - what it is and what it does
https://knowledge.broadcom.com/external/article?articleId=34717
How to clear the niscache on an individual robot
https://knowledge.broadcom.com/external/article/44669
Attached niscache_clean_2.1 to case which can be dragged and dropped to clean the niscache on any robot.