Patent ID: 7600087
Filing Date: 2009-10-06
Classification: G06F

Abstract:
1. A remote copy system, comprising: first and second primary storage subsystems, the first primary storage subsystem including a first primary volume, the second primary storage subsystem including a second primary volume, the first and second primary volumes storing a plurality of write data in a given order; an intermediate storage subsystem coupled to the first and second primary storage subsystems and configured to synchronously receive the write data from the first and second primary storage subsystems, the intermediate storage subsystem including a write-order-information provider that is configured to generate write-order information for the write data received from the first and second primary storage subsystems, the write-order information provider comprising a counter that generates a sequence number forming part of the write-order information, the write-order information being associated with the write data received from the first and second primary storage subsystems, the write-order information reflecting the given order of storage of the write data in the first and second primary storage subsystems, wherein the intermediate storage subsystem includes first and second intermediate volumes defined as a consistency group within which data integrity is guaranteed, the first intermediate volume being configured to receive the write data from the first primary volume, the second intermediate volume being configured to receive the write data from the second primary volume; first and second secondary storage subsystems coupled to the intermediate storage subsystem and configured to asynchronously receive the write data from the intermediate storage subsystem, the first secondary storage subsystem including a first secondary volume that is configured to mirror the first primary volume of the first primary storage subsystem which is a separate storage subsystem from the intermediate storage subsystem, the second secondary storage subsystem including a second secondary volume that is configured to mirror the second primary volume of the second primary storage subsystem which is a separate storage subsystem from the intermediate storage subsystem, wherein the write data are stored in the first and second secondary storage subsystems according to the write order information associated with the write data as generated by the write-order-information provider of the intermediate storage subsystem which is a separate storage subsystem from the first primary storage subsystem having the first primary volume and the second primary storage subsystem having the second primary volume; and a valid counter forming part of the intermediate storage subsystem, the valid counter being configured to keep the highest sequence number of the write data that is ready to be validated for copying at the secondary subsystems, wherein the intermediate storage subsystem transmits a request to prepare the write data and transmits a request to validate the write data which has been prepared according to the prepare request, based on a value of the valid counter.