I was wondering where "autosave" saves can be found. I mean where does it save to??? All I know is that it is set for 5 min intervals when set at 6000 ticks.
Autosave means saving the world, much like when you pause your game in single player and the game automatically saves the world in the background. Without autosave, the only time the server would be saving on it's own is when it shuts down, so if the server were to crash any progress from the time when the server started to the time when it crashed would be lost.
If you're looking for a backup function, there's one built into Essentials, and there are many other backup plugins.