Personally, I would recommend writing (or googling and finding) your own backup script / software.
The reason I think this is because this script works externally from the Minecraft server instance and isn't dependent on it being running, so should the server crash you'll still get the scheduled backup you're used to.
Also, scripts are very customisable with little programming experience whatsoever, however, mods/plugins aren't.
There are many resources on the internet for Linux and Windows sytems alike to automate backups of a directory, so I'd recommend going down that route.
~Rob