Abstract: An apparatus, method, and computer program for facilitating disaster recovery of a first computer system, wherein first data residing on a first storage device associated with the first computer system is recoverable from second data residing on a second storage device associated with a second computer system and wherein the second storage device is operable to have an associated state of powered up or powered down. A receiver receives an update operation for updating the second storage device. A processor updates anon-volatile storage means with the update operation, prior to update of the second storage device, wherein the non-volatile storage means is associated with the second computer system.

Abstract: An apparatus, method, and computer program for facilitating disaster recovery of a first computer system, wherein first data residing on a first storage device associated with the first computer system is recoverable from second data residing on a second storage device associated with a second computer system and wherein the second storage device is operable to have an associated state of powered up or powered down. A receiver receives an update operation for updating the second storage device. A processor updates anon-volatile storage means with the update operation, prior to update of the second storage device, wherein the non-volatile storage means is associated with the second computer system.

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 method and apparatus is disclosed in which a storage controller cooperable with a host and a plurality of controlled storage is provided to localize an impact of a failure to a target disk in an affected segment. The storage controller includes a host write component to write a data object to a source image storage; a first copy component responsive to a first metadata state to control copying of the data object to a first target storage; a second copy component responsive to a second metadata state to perform either: copying the data object to a second target or causing the first copy component to copy the second target to the first target; and a third copy component to control cascaded copying of the data object to a third target storage. Either the second or the third copy component controls cascaded copying of a delimited data image subsequence responsive to a metadata state indicating currency of a data grain in either the second or the third target.