Prefetching source tracks for destaging updated tracks in a copy relationship

A system for maintaining a copy relationship between tracks in a source storage and a target storage, comprising:

• a processor;
• a cache device;
• and
• a computer readable storage medium having computer readable program code embodied therein executed by the processor to perform operations, the operations comprising:
• maintaining a point-in-time copy relationship associating tracks in the source storage with tracks in the 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 the cache device;
• and
• 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 before destaging the updated source track to the source storage.

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 cache device;
• and
• 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 before destaging the updated source track to the source storage.