| Consumer cloud storage(CCS) is a new generation of cloud storage service. It utilizes apps installed on user's devices to automatically store files in the cloud, and synchronizes files across multiple devices via the cloud. However, existing CCS has severe limitations on networking performance, service reliability, data security and vendor lock-in threat.To overcome these limitations, CCS middleware utilizes the public Web APIs provided by CCSs to integrate them into a multi-cloud. The middleware follows a distributed design in which all the synchronization logic is implemented at the client devices, so as to avoid the reliability issue and performance bottleneck caused by the introduction of a server. Since it only uses the basic file access APIs of the CCSs, the middleware guarantees the consistency of the metadata during the synchronization process through a novel distributed mutual-exclusive locking protocol. User files are sliced and erasure coded to generate redundant data blocks, which are scattered to all the available clouds to maximize parallel data transfer and achieve higher reliability. However, the key techniques to boost networking performance are data block over-provisioning and dynamic scheduling, which mask the heterogeneous performance of different CCSs and exploit more the faster clouds to speed up the file transfer.CCS middleware is implemented on the Windows platform, and are compared with 5 famous CCS products on the Amazon EC2 platform covering 7 datacenters, 6 countries and 5 continents. The results show that CCS middleware not only has better reliability and security, but also achieves higher and more stable networking performance, the average speed improvement is about 2.64 times for upload, 1.49 times for download and 1.33 times for synchronization over the best of the 5 CCSs. What's more, traces from 272 users along a one month period of real-world trial confirms CCS middleware's superior in the wild. |
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