Patent ID: 8656104

Claim:
A method, comprising: maintaining a point-in-time copy relationship associating tracks in a source storage with tracks in a target storage, wherein the target storage stores the tracks in the source storage as of a point-in-time; receiving a write request including an updated source track for a point-in-time source track in the source storage in the point-in-time copy relationship, wherein the point-in-time source track was in the source storage at the point-in-time the copy relationship was established; storing the updated source track in a first cache device; sending a prefetch request to the source storage to prefetch the point-in-time source track in the source storage subject to the write request to a second cache device; generating a read request to read the source track in the source storage following the sending of the prefetch request; and copying the read source track to a corresponding target track in the target storage.