We are running an instance of Matomo that is monitoring more than a 1000 websites so far.
Since a few months the archiving process start to cause us some issues. It can run sometimes for more than a day (without any error).
We have tried to increase the number of concurrent archivers ( --concurrent-archivers ) but it seems not to work. I don’t see a different number in the logs like mention in the documentation here: https://fr.matomo.org/faq/on-premise/how-to-set-up-auto-archiving-of-your-reports/
We are running in 3.14.1 still
Don’t hesitate to ask for more information I’ll be appy to share !