The question is for ActiveMQ on a Data Collector. We had an issue with disk space the other day and while looking for the files that were using the most space we ran across this dir, /opt/IMDataCollector/broker/apache-activemq-5.15.2/data/dc_broker_bfbcf803-2f66-4590-98f7-59c15a9a49ab/tmp_storage.
There were over 2000 files in there which equaled around 60GB of space being used. Using Google I found out about a file called activemq.xml in /opt/IMDataCollector/broker/apache-activemq-5.15.2/conf. This file listed the tempUsage value as "<tempUsage limit="200 gb"/>".
Is this the value to set how big the tmp_storage directory can grow? If so 200 GB is more than the free space available on the system.
Restarting AMQ causes that directory to be cleaned up. It's the temp storage for caching data AMQ uses. I don't think AMQ reduces the size of the file, but can expand as needed. We ship with 200GB OOTB set, but during AMQ startup, it checks the disk for free space available and re-adjusts to the free disk space available. You can adjust the XML yourself, but not 100% sure we preserve that setting during upgrade. Reducing the size too much will result in less caching of poll messages if the DA is unreachable.