Patent ID: 7188223

Claim:
In a data storage environment having a first volume of data denominated as the source being stored on a data storage system, and a second volume of data denominated as the clone and which has data content that is a copy of the data content of the source being stored on the data storage system or on another data storage system, a method of managing data content during a restoration of the source, the method comprising the steps of: restoring the source by copying data content from the clone to overwrite the data content of the source in a copy-on-demand process: receiving a host write request during the restoring step; determining extents on the source that would be affected by the host write request if carried out; executing restoration of the affected source extents in a manner to allow the host write request to be processed as soon as the required extents have been copied from the clone to the source; and setting an indicator to indicate that the affected extents need to be re-copied.