Information that is stored in a cloud server is usually "guaranteed" to be backed up and is redundant. When one stores information on a cloud server one cannot control exactly where it is stored. Obviously, it sits on a hard drive somewhere in a server farm but the user has no knowledge of that.
For mission critical data some designers choose not entrust that to the cloud or synchronise it and back it up via their own servers. Any such data can be periodically download into your own local server which is accessible to the internet via the appropriate firewalls and security measure.
As the cloud industry grows and systems are increasingly designed to work in the cloud, reputable providers will be trusted to provide a highly secure and a highly redundant back-up service.