Maintaining duplex-paired storage devices during gap processing using of a dual copy function

摘要

A technique is described for managing data storage devices and the data stored on them. A pair of data storage devices are maintained as identical copies. The dual copy function is provided without changing any current system or application software on the host. A set of status information is maintained for each record on the data storage devices. This status information includes information which allows only the changed records to be copied to a secondary device of the dual copy. This technique also provides high availability of data storage devices by swapping a failing data storage device with a good data storage device without host intervention. A joint array structure is used for routing host requests for information to and from the correct data storage device and keeping status information concerning the data storage devices.