How much of the cloud infrastructure is redundant?
Redundancy offers security in the sense that your applications will be there almost no matter what happens to you cloud provider's own infrastructure.
Most cloud providers offer to automatically protect your data by running independent and geographically distinct data centers, so that your infrastructure will continue running even if one of their data centers fails. It doesn't hurt to ask before you start using the service. Amazon, for example, has several distinct "zones" in North America, Asia, and Europe where its servers are located. A user can specify the location of his virtual servers and design an environment to be protected in case of any failures. A more complete discussion of the various security decisions involved in using Amazon's Web Services can be found here. For the US Golf Association, Carroll built in the requirement that the vendor provide a hot site at another location in case of any downtime. "We pay a bit more for this redundancy, but it gives us a level of comfort too."