* The most relevant is the logs folder, as there are the logs.
* Second most relevant ist the threaddumps folder, where the periodically created threaddumps are stored.
* in "repository" the binaries of the repository are stored.
* ignore app, conf, launchpad folders.
* bin -- the start/stop scripts
ps: It would be good if you can tell us what exactly you are looking for, then the answers can be more specific. Just asking for curiosity is a understandable motivation, but then I would answer: Go and try to find out yourself first 🙂