Open-source library request: A library that lets you use S3 and Google Storage Cloud simultaneously and fail-back to another if one have problems. There are many use-case when paying 2x for storage is a reasonable tradeoff for higher availability and also be provider independent.
https://jclouds.apache.org/
Apache jclouds® is an open source multi-cloud toolkit for the Java platform that gives you the freedom to create applications that are portable across clouds while giving you full control to use cloud-specific features.