Patent ID: 6757797
Filing Date: 2004-06-29
Classification: G06F

Abstract:
A copy method for copying data from a copy-source logical disk to a copy-destination logical disk according to a copy instruction from a host, comprising:notifying the host of a copy completion upon receipt of the copy instruction; copying, in units of each area dividing the copy-source logical disk, from the copy-source logical disk to the copy-destination logical disk; interrupting said copying in response to an access request; from the host; and allowing access to the copy-source logical disk and copy-destination logical disk according to an access request during said copying, wherein said copying further includes: referencing control information that indicates a copying condition of the areas, and setting control information of a next copy area; and updating the control information for the copy area after said copying of the copy area has finished, and wherein said allowing of access includes: referencing the control information and determining whether a target access area of an access request is a copied area or uncopied area; copying the target access area of the copy-source logical disk to the copy-destination logical disk and then updating the target access area of the copy-source logical disk when the access request is a request for updating an uncopied area of the copy-source logical disk; and referencing the target access area of the copy-source logical disk when the access request is a request for referencing an uncopied area of the copy-destination logical disk, and updating the target access area of the copy-destination logical disk and prohibiting copying of data from the copy-source logical disk to the target access area when the access request is for the updating of an uncopied area of said copy-destination logical disk.