Cloud-of-Clouds provides？

1. Fault-tolerance ：容错
2. Security ：通过编码或者secret splitting 提供安全存储

Papers about Cloud-of-Clouds

1. DepSky – Dependable and Secure Storage in a Cloud-of-Clouds【Eurosys11】
2. NCCloud: Applying Network Coding for the Storage Repair in a Cloud-of-Clouds【FAST12】

What we can do next？

1. Using Cloud-of-Clouds provides secure storage with costing less space and less flow.