US Patent 8712982 Virtual multi-cluster clouds

An improved scalable object storage system allows multiple clusters to work together. Users working with a first cluster, or with a multi-cluster gateway, can ask for services and have the request or data transparently proxied to a second cluster. This gives transparent cross-cluster replication, as well as multi-cluster compute or storage farms based upon spot availability or various provisioning policies. Vendors providing a cloud storage “frontend” can provide multiple backends simultaneously. In one embodiment, a multi-cluster gateway can have a two, three, or higher-level ring that transparently matches an incoming request with the correct cluster. In the ring, a request is first mapped to an abstract “partition” based on a consistent hash function, and then one or more constrained mappings map the partition number to an actual resource. In another embodiment, the multi-cluster gateway is a dumb gateway, and the rings are located only at the cluster level.