We use Amazon’s S3 service to backup your data. S3 provides a highly durable storage infrastructure designed for mission-critical and primary data storage. Objects are redundantly stored on multiple devices across multiple facilities in an Amazon S3 Region. To help ensure durability, Amazon S3 PUT and COPY operations synchronously store your data across multiple facilities before returning SUCCESS. Once stored, Amazon S3 maintains the durability of your objects by quickly detecting and repairing any lost redundancy. Amazon S3 also regularly verifies the integrity of data stored using checksums. If corruption is detected, it is repaired using redundant data. In addition, Amazon S3 calculates checksums on all network traffic to detect corruption of data packets when storing or retrieving data.

Amazon S3’s standard storage is:

• Backed with the Amazon S3 Service Level Agreement.
• Designed to provide 99.999999999% durability and 99.99% availability of objects over a given year.
• Designed to sustain the concurrent loss of data in two facilities.

Amazon S3 provides further protection via Versioning. We use Versioning to preserve, retrieve, and restore every version of every object stored in our Amazon S3 bucket. This allows us to easily recover from both unintended user actions and application failures. By default, requests will retrieve the most recently written version. Older versions of an object can be retrieved by specifying a version in the request. Storage rates apply for every version stored.