Patent ID: 7360047
Filing Date: 2008-04-15
Classification: G06F

Abstract:
1. A storage system for redundant writing of data from a host computer into a first volume of a first storage apparatus and a second volume of a second storage apparatus, said storage system performing processes comprising: a first process in which information including update data from said host computer in said redundant writing is retained in said first storage apparatus as first update data history information and in said second storage apparatus as second update data history information; and when one of a first redundant writing system including said first storage apparatus and a path from said host computer to said first volume and a second redundant writing system including said second storage apparatus and a path from said host computer to said second volume changes into a failed state where I/O is impossible while the other one of the redundant writing systems remains normal, second and third processes are preformed to return said failed redundant writing system back to a normal state where said redundant writing is possible, a second process in which said first and second storage apparatuses communicate with each other regarding the update data history information of the storage apparatus of the normal redundant writing system, data after a latest synchronization point required for synchronization of data contents of said first and second volumes is copied and transferred not through said host computer but directly from the storage apparatus of the normal redundant writing system to the storage apparatus of the failed redundant writing system which is to be recovered; and a third process in which the storage apparatus of said failed redundant writing system reflects the copied data onto the volume thereof based on the update data history information obtained through transfer between said storage apparatuses to synchronize said first and second volumes.