Abstract: A method for performing a write to a volume x in a cascaded architecture is described. In one embodiment, such a method includes determining whether the volume x has a child volume, wherein each of the volume x and the child volume have a target bit map (TBM) associated therewith. The method then determines whether the TBMs of both the volume x and the child volume are set. If the TBMs are set, the method finds a higher source (HS) volume from which to copy the desired data to the child volume. Finding the HS volume includes comparing ages of mapping relationships upstream from the volume x in order to determine a source of the data. Once the HS volume is found, the method copies the data from the HS volume to the child volume and performs the write to the volume x. A method for performing a read is also disclosed herein.

Abstract: A method for deleting a relation between a source and a target in a multi-target architecture is described. The multi-target architecture includes a source and multiple space-efficient (SE) targets mapped thereto. In one embodiment, such a method includes initially identifying a relation for deletion from the multi-target architecture. A space-efficient (SE) target associated with the relation is then identified. A mapping structure maps data in logical tracks of the SE target to physical tracks of a repository. The method then identifies a sibling SE target that inherits data from the SE target. Once the SE target and the sibling SE target are identified, the method modifies the mapping structure to map the data in the physical tracks of the repository to the logical tracks of the sibling SE target. The relation is then deleted between the source and the SE target.

Abstract: A method for deleting a relation between a source and a target in a multi-target architecture is described. The multi-target architecture includes a source and multiple space-efficient (SE) targets mapped thereto. In one embodiment, such a method includes initially identifying a relation for deletion from the multi-target architecture. A space-efficient (SE) target associated with the relation is then identified. A mapping structure maps data in logical tracks of the SE target to physical tracks of a repository. The method then identifies a sibling SE target that inherits data from the SE target. Once the SE target and the sibling SE target are identified, the method modifies the mapping structure to map the data in the physical tracks of the repository to the logical tracks of the sibling SE target. The relation is then deleted between the source and the SE target. A corresponding computer program product is also described herein.