Server rollback issues

I have server with some friends of mine. Everything is going fine but sometimes the server shuts down and restarts but when we join back there is a small rollback. This was a minor issue and i didn't want to drag attention away from more important problems. The problem is that the previous rollback rolled back alot. For example: me and a friend were racing advancements but after the rollback that just happenend all advancements from every player that was/is on the server is gone. The rollback is also more severe then previous rollbacks. I hope there is a way I can prevent this in the future and possibly get back the rolledback stuff(like the advancements).