Patent ID: 6842835
Filing Date: 2005-01-11
Classification: G06F

Abstract:
1. A storage apparatus comprising: a first storage subsystem for connection to a plurality of host computers via a first interface; a second storage subsystem connected to the first storage subsystem via a second interface so as to copy write data written in the first storage subsystem from the host computers onto the second storage subsystem from the first storage subsystem, thereby protecting the write data in the first and the second storage subsystems in a multiplex manner; and a storage control unit for the first storage subsystem, having: a first threshold for controlling for each of the host computers an occupancy ratio of the write data whose copy to the second storage subsystem is incomplete in a data buffer in the first storage subsystem, and control logic for delaying the processing of a data write request from each of the host computers on the basis of the first threshold which is set for each of the host computers, wherein data received from at least one of the host computers is converted to a format compatible with transfer to the second storage subsystem, prior to copying thereof to the second storage subsystem.