Managing point-in-time copies for extents of data

A system for managing a copy between a source storage and a target storage, comprising:

• a processor;
• and
• a computer readable storage medium having program instructions executed by the processor to perform operations, the operations comprising:
• receiving an establish point-in-time copy command from a host including at least one range of extents in at least one volume in the source storage and a point-in-time copy identifier, wherein the host generates the point-in-time copy identifier to provide a unique identifier for a point-in-time copy to establish with the establish point-in-time copy command, wherein the at least one range of extents comprises less than all the extents included in the at least one volume;
• establishing a point-in-time copy identified by the point-in-time copy identifier and for the at least one range of extents in the establish point-in-time copy command
• generating a change recording information indicating each of the at least one range of extents less than all of the extents in the at least one volume;
• receiving an update to data in the at least one range of extents in the point-in-time copy;
• copying the data in the source storage in the at least one range of extents to be updated as changed data to the target storage, wherein the changed data stored in the target storage includes the point-in-time copy identifier of the point-in-time copy for which the data is copied;
• and
• indicating in the change recording information the data in the at least one range of extents that has been updated.

A method for managing a copy between a source storage and a target storage, comprising:

• receiving an establish point-in-time copy command from a host including at least one range of extents in at least one volume in the source storage and a point-in-time copy identifier, wherein the host generates the point-in-time copy identifier to provide a unique identifier for a point-in-time copy to establish with the establish point-in-time copy command, wherein the at least one range of extents comprises less than all the extents included in the at least one volume;
• establishing a point-in-time copy identified by the point-in-time copy identifier and for the at least one range of extents in the establish point-in-time copy command
• generating a change recording information indicating each of the at least one range of extents less than all of the extents in the at least one volume;
• receiving an update to data in the at least one range of extents in the point-in-time copy;
• copying the data in the source storage in the at least one range of extents to be updated as changed data to the target storage, wherein the changed data stored in the target storage includes the point-in-time copy identifier of the point-in-time copy for which the data is copied;
• and
• indicating in the change recording information the data in the at least one range of extents that has been updated.