Patent ID: 8555019

Claim:
A computer program product for migrating data from a source storage to a destination storage, the computer program product comprising a computer readable storage medium having computer readable program code embodied therein that executes to perform operations, the operations comprising: indicating in an extent list tracks in an extent in the source storage subject to Input/Output (I/O) requests; initiating a migration operation to migrate the extent from the source storage to the destination storage; and in response to initiating the migration operation, performing: determining a first set of tracks in the extent in the source storage indicated in the extent list based on an access characteristic of the tracks in the extent; determining a second set of tracks in the extent, wherein the second set of tracks have the access characteristic to a lesser extent than the first set of tracks; copying the tracks in the source storage in the first set to a migration cache, wherein updates to the tracks in the migration cache during the migration operation are applied to the migration cache; copying the tracks in the second set directly from the source storage to the destination storage without buffering in the migration cache; copying the tracks in the first set from the migration cache to the destination storage; and completing the migration operation in response to copying the first set of tracks from the migration cache to the destination storage and copying the second set of tracks from the source storage to the destination storage, wherein after the migration the tracks in the extent are located in the destination storage.