Patent ID: 8396830
Filing Date: 2013-03-12
Classification: G06F

Abstract:
1. A data control method for duplicating data in a system which includes a primary system including a first computer system and a first storage device connected to said first computer system, and a secondary system including a second computer system and a second storage device connected to said second computer system, wherein at least said first storage device and said second storage device are connected to each other, said data control method comprising the steps of: storing a log, in a disk device within said first storage device, that is used to generate an update of data, said data being produced as a result of processing performed by said first computer system and being stored in said first storage device; copying said log stored in said disk drive within said first storage device to a disk drive within said second storage device, said disk device within said second storage device being set to duplicate said log; updating said data stored in said first storage device, said data being produced as a result of said processing performed by said first computer system; detecting a change in data stored in said disk drive within said second storage device, said change being made as a result of performing said copying step by said second computer system; reading, by second computer system, said change in said data stored in said disk device within said second storage device; and reading, by said second computer system, said log copied to said disk drive within said second storage device and updating a duplicate of said data, stored in said first storage device, based on said log copied to said disk drive within said second storage device, said duplicate being stored in said second storage device, wherein a log unit of storing said log stored in said disk device within said first storage device is specified by said first computer system, and wherein a log unit of reading said log stored in said disk device within said first storage device is specified by said second computer system.