How does the cache behave on server shutdown?

Hello everybody.

The following happened today:

On our 3.9.1 openfire we had a bot running spamming rooms with messages (this was done on purpose).

We also have the Archiving Plugin running.

Before the shutdown the ofMessageArchive got 7k entries...so, 7k messages.

The ofMucConversationLog has only 700 entries....I believe this was due to most messages beeing cached.

We then restarted openfire.

The ofMucConversationlog was still at only 700 entries....so, where did all the messages go?

All of our RoomHistories for every MUCRoom did loose all their messages.

Something really fishy is going on here.

So, my question is what happens with the cache on server shutdown.

Is it written to the Database or dumped in a file and then read on server start again?

Thanks in advance.