Optimization of the copying of change recorded data by using spare flash capacity

摘要

A command is received to copy a first extent in a source volume to a second extent in a target volume, wherein the source volume and the target volume are in a copy relationship. In response to determining that it takes longer to copy all changed data of the first extent to the second extent than to copy all of the changed data of the first extent to a third extent and to copy all other data from the second extent to the third extent, operations are performed to copy all of the changed data of from the first extent to the third extent and to copy all of the other data from the second extent to the third extent. Operations are also performed to assign the third extent to replace the second extent in the target volume.