Abstract: Illustrative embodiments provide a computer implemented method for incremental storage de-allocation during a clean process within a point-in-time copy storage management system. The computer implemented method determines whether to perform the clean process and responsive to a determination to perform the clean process, determines whether a set of discrepant bits is present. Responsive to the determination that the set of discrepant bits is present, the computer implemented method copies each dirty grain for each discrepant bit in the set of discrepant bits to a downstream target to form a set of copied dirty grains and determines whether a particular dirty grain in the set of copied dirty grains has been allocated to a space efficient storage unit. Responsive to a determination that the particular dirty grain was allocated to a space efficient storage unit, the computer implemented method de-allocates the particular grain from an upstream source.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.

Abstract: Illustrative embodiments provide a computer implemented method for incremental storage de-allocation during a clean process within a point-in-time copy storage management system. The computer implemented method determines whether to perform the clean process and responsive to a determination to perform the clean process, determines whether a set of discrepant bits is present. Responsive to the determination that the set of discrepant bits is present, the computer implemented method copies each dirty grain for each discrepant bit in the set of discrepant bits to a downstream target to form a set of copied dirty grains and determines whether a particular dirty grain in the set of copied dirty grains has been allocated to a space efficient storage unit. Responsive to a determination that the particular dirty grain was allocated to a space efficient storage unit, the computer implemented method de-allocates the particular grain from an upstream source.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.

Abstract: A storage controller includes an interface to host computer apparatus and an interface to a plurality of controlled storage apparatus. The storage controller comprises a host write component operable to send a request to write a data object to a source data image at one of said plurality of controlled storage apparatus; a copy component operable in response to a metadata state to control copying of said data object to a target data image in a delimited sequence of data images in a cascade at said plurality of controlled storage apparatus and a fill-in component operable in response to detection of an offline condition of a disk containing said target data image to control substitution of a fill-in disk in place of said disk containing said target data image.