Patent ID: 8825973

Claim:
A computer program product for processing a read operation for a target block of data, the computer program product comprising a computer readable storage medium having computer readable program code embodied therein, wherein the computer readable program code, when executed by a processor of a computer, performs operations, the operations comprising: receiving the read operation for the target block of data in target storage, wherein the target block of data is in an instant virtual copy relationship with a source block of data in source storage; determining that the target block of data in the target storage is not consistent with the source block of data in the source storage; retrieving the source block of data; synthesizing data in the source block of data in a cache to make the data appear to be retrieved from the target storage; marking the target block of data as read from the source storage; in response to the read operation completing, demoting the target block of data that was read from the source storage; and in response to receiving a withdraw command that ends the instant virtual copy relationship, ending the instant virtual copy relationship without scanning the cache and discarding target blocks of data staged from the source storage.