But please be careful because if you use anything based on automatic synchronisation, such as RAID or a DropBox-like service, there is also a danger that anything you accidentally delete or corrupt will then propagate. If there’s no historical version saved as part of the system, or if there is but you don’t notice the problem before it disappears, you can end up damaging your “backup” copies of your data in exactly the same way as the original if something goes wrong.