Patent ID: 6092066
Filing Date: 2000-07-18
Classification: G06F,Y10S

Abstract:
A method for operating first and second data processing systems interconnected by a communications link, each system being capable of independent operation and including a host computer and a data storage facility that stores data at predetermined locations in data blocks, the second system, during a normal operating mode, constituting a mirror for the data in the data storage facility of the first system, said method comprising:(A) enabling an independent operating mode of each of the first and second systems by disabling transfers through the communications link and enabling the independent operation of each of the first and second systems,(B) recording in the data storage means of the first system an identification of each data block that changes as a result of the operation of the first system,(C) recording in the data storage means of the second system an identification of each data block that changes as a result of the operation of the second system,(D) enabling the communications link upon completion of the independent operations thereby to return to the normal operating mode, and(E) thereafter, and independently of the first data system:(i) combining the recorded identifications to identify all the data blocks that were changed in the data storage means of the first and second systems, and(a) copying from the data storage facility in the first system to the data storage facility in the second system the data blocks corresponding to the combined recorded identifications thereby to reestablish the data storage facility in the second data processing system as a mirror of the data storage facility in the first data processing system.