US Patent 10359968 Smart data movement among virtual storage domains

Virtual storage domains (VSD) are each associated with unique VSD domain ID associated with a first policy and tagged to a request to a storage system when an entity writes a data set to it. A first hash digest, based on data set content, is calculated and combined with first unique VSD domain ID into a second hash digest associated with data set. When first policy is changed to second policy associated with second VSD, a third hash digest of first data set is calculated, the third hash digest based on content of first data set and on second unique VSD domain ID. If third hash digest does not exist in second VSD, data set is copied to the second VSD; else, reference count of the third hash digest, associated with second VSD domain, is incremented, and reference count of second hash digest, associated with first VSD domain, is decremented.