Patent ID: 9081511
Filing Date: 2015-07-14
Classification: G06F

Abstract:
1. A computer program product, for use with a host, a storage controller and source and target storage devices having extent ranges, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therein that executes to perform operations, the operations being in the storage controller, the operations comprising: mapping in a plurality of maps for a target storage device, map extent ranges of each map, to corresponding target extent ranges of storage locations on the target storage device; indicating for a particular map extent range of a particular map, that the particular map extent range of the particular map is available for the establishment of a relationship between a source extent range of storage locations on a source storage device containing data to be preserved in the source extent range, and the target extent range mapped to the map particular extent range; receiving a data preservation command identifying a source extent range containing data to be preserved on the source storage device, and identifying a target extent range on the target storage device; and in response to the command, performing a data preservation operation including: determining whether a map indicates availability of a map extent range mapped to the identified target extent range; and upon determining that a particular map indicates availability of a map extent range mapped to the identified target extent range, establishing a relationship between the identified source extent range and the identified target extent range; wherein said indicating further includes indicating usage of the particular map extent range of the particular map by the relationship; and storing in a data structure for the relationship, an identification of the particular map which indicates usage of the particular map extent range of the particular map by the relationship.