A hybrid storage appliance is a physical or virtual storage caching system that destages local or on-site data storage to the cloud instead of to back-end disks. In every other way, it behaves as a storage system. The term “hybrid” describes the fact that the appliance combines local storage with cloud storage, usually public cloud storage that is geographically distant from the appliance. From a data flow perspective, it is a storage target or an in-band appliance that intercepts all input/outputs (I/Os) to and from a virtual volume or file system. From a storage system perspective, it uses sophisticated cache management algorithms to minimize data flows to and from the cloud by satisfying as many I/Os as possible from local storage. Data is compressed or deduplicated in the appliance to increase its effective cache capacity, and when data is actually transferred to or from the cloud, WAN-optimized controller (WOC) techniques are often used to reduce the impact of link latency on performance.