Scania crashed! XD

From what I understand, what people call a "rollback" is what happens when the server crashes because it doesn't immediately write changes in exp and such to disk because writing to disk is slow compared to memory. I know that changing channel, going into MTS/CS, and logging out forces it to write your data to disk and there might be other things too. I think it might also do it periodically, but I'm not entirely sure.