Patent ID: 6578120
Filing Date: 2003-06-10
Classification: G06F

Abstract:
A system for copying data, comprising:a first storage system; a second storage system; means for copying data from the storage locations in the first storage system to the second storage system by copying data in consecutive storage locations from a lowest storage location address to a highest storage location address in the first storage system to consecutive storage locations in the second storage system from a lowest storage location address to a highest storage location address; means for determining a last storage location address in the second storage system receiving the data consecutively copied from the storage locations in the first storage system; means for detecting update data to one storage location in the first storage system while copying data from storage locations in the first storage system to the second storage system; means for storing the update data to the first storage system; means for transmitting the detected update data to the second storage system; and means for applying the update data to the second storage system in a manner that maintains consistency between data copied from the storage locations and update data by: (i) determining whether received update data is to a target storage location address in the second storage system that is less than the determined last storage location address; (ii) writing the received update data to the target storage location if the target storage location address is less than the determined last storage location address; and (iii) delaying the writing of the received update data while data from further storage locations in the first storage system is copied to the second storage system until the determined last storage location address is greater than the last storage location address.