Patent ID: 6981008
Filing Date: 2005-12-27
Classification: G06F,Y10S

Abstract:
1. A computer-implemented method of duplicating data in a system provided with a first storage subsystem group, comprising a first plurality of storage subsystems, and a second storage subsystem group, comprising a second plurality of storage subsystems, wherein the storage subsystems of the second storage subsystem group store copies of the data of the first storage subsystem group, wherein each of the storage subsystems of the first storage subsystem group writes the data into a storage device of the first storage subsystem group, assigns a serial number and a time, and transfers the data through a transmission line to at least one of the storage subsystems of the second storage subsystem group, and wherein a plurality of data received by each of the storage subsystems of the second storage subsystem group is arranged sequentially based on the serial numbers, and wherein an oldest time is decided from among a plurality of latest times by each of storage subsystems of the second storage subsystem group, each latest time being related to the plurality of data arranged based on the serial numbers, each latest time being communicated for comparison between at least some of the storage subsystems of the second storage subsystem group, and wherein data that is related to a time not later than the decided oldest time are selected as data to be written to the storage device of each of the storage subsystems of the second storage subsystem group, wherein one of the storage subsystems of the second storage subsystem group is a predetermined storage subsystem and each of the storage subsystems, other than the predetermined storage subsystem, notifies the predetermined storage subsystem of a latest time of data from the other storage subsystems, and the predetermined storage subsystem decides the oldest time from among the latest time of data in each of the other storage subsystems and a latest time of data stored in the predetermined storage subsystem.