Patent ID: 8230185

Claim:
A method implemented in a computer infrastructure having computer executable code tangibly embodied on a computer readable storage medium having programming instructions operable to: determine whether a target disk of a map contains data unavailable to a downstream disk from an upstream disk in a FlashCopy cascade; detect whether the downstream disk has a copy of the data; copy the data from the target disk to the downstream disk, if the target disk of the map contains data unavailable to the downstream disk from the upstream disk and the downstream disk does not have the copy of the data; refrain from copying the data from the target disk to the downstream disk, if the target disk of the map does not contain data unavailable to the downstream disk from the upstream disk or the downstream disk does have the copy of the data; and remove the map from the FlashCopy cascade, wherein the map is an incremental map comprising: a spilt bitmap value indicating whether the target disk contains an actual copy of data for a particular grain or relies on a source disk containing the data for the particular grain; and a difference bitmap value indicating whether data contained on the particular grain of the target disk is different from data contained on a corresponding grain of the source disk; and a split bitmap value of zero for the particular grain and a difference bitmap value of zero for the particular grain indicates that the target disk of the map does not contain data for the particular grain unavailable to the downstream disk from the upstream disk.