@mstan — sorry that you haven't received a response.
NodeBB doesn't save the Mongo database anywhere specific on the file system, it would be wherever the insulted MongoDB install saves it's data.
since about 2-3 days I have a bug where the daily stats show zero. It seems that NodeBB still counts stats (Today / Yesterday) but the chart is empty. Before that I had a reboot followed by a Clear Linux Kernel and system updated (rolling release), but no Node.js update or Redis update was done as those are manual.
That's odd, I'll say we haven't seen this before... is it just stats that are wonky, and not anything else? Stats missing like this usually indicate that maybe the database isn't persisting to disk, but if that was the case, the dashboard stats would be the least of your worries...
Hmm, I also noticed that a new user account registration was pending approval, but a click on the little red indicator icon lead to no redirection. Only something like "show all notifications" finally showed me the approval queue, where than a click on the green icon also lead to no further actions. Seems the Admin panel is a bit shaky now. NodeBB runs inside VMware, no crash or so happened with weekly backups of the VM.
The core forum functions are working, so no big deal. If it falls apart I report back