Method for duplicating data of storage subsystem and data duplicating system

Abstract

In order to realize asynchronous type system assuring the consistency of data with the function of disk subsystems without the need of introducing new software to a host unit and without the deterioration of the performance of a main center, in a remote copy system which copies the data to the disk subsystems of the remote center for duplicating the data in the disk subsystems of the main center, the disk subsystems give serial numbers and times to the data together with writing said data to the storage devices in the disk subsystem and transfer said data to the other disk subsystems, and the other disk subsystems arrange the two or more data in the sequence of the serial numbers, decide the oldest time among the latest time given to each of the disk subsystems communicating among the disk subsystems and the data given with the time not later than the decided oldest time are the objects of writing to each of the disk storage devices.

1 . A storage subsystem, wherein a storage subsystem belongs to a storage subsystem group comprising a plurality of storage subsystems and said storage subsystem being provided with 
 a first means of writing data received from outside to the storage device of the storage subsystem,    a second means of transmitting said data being given a serial number and a time to other storage subsystems,    a third means of arranging a plurality of data received from other storage subsystems in sequence of said serial numbers, and    a fourth means of deciding the oldest time among the kinds of latest time given to each of the storage subsystems by communicating at least some of the latest times between at least two storage subsystems for comparison,    wherein the storage subsystem operates the first means and the second means when said storage subsystem is in local mode, and decides the data given with the time not later than the decided oldest time as the object of writing data by the first means operating the third means, the fourth means, and the first means at the remote mode.    
   
   
       2 . A storage subsystem as claimed in  claim 1 , wherein said storage subsystem operating in said local mode is connected with said storage subsystem operating in said remote mode through a Storage Area Network (SAN).  
   
   
       3 . A storage subsystem as claimed in  claim 1 , wherein said storage subsystem comprises a means for correcting a clock which is for referring to said time by time information from an external source.  
   
   
       4 . A storage subsystem as claimed in  claim 1 , wherein a loop transmission line connects among said storage subsystems operating in said remote mode and each of the storage subsystems in said remote mode comprises a means of transmitting the older time among said own latest time and received said latest time to an adjacent storage subsystem and a means of deciding the time transferred by the own storage subsystem and returned to the own storage subsystem as said oldest time.  
   
   
       5 . A storage subsystem as claimed in  claim 1 , wherein one of said storage subsystems which operates in said remote mode is arranged as a master storage subsystem, each of the storage subsystems other than said master storage subsystem comprises a means for notifying said latest time to said master storage subsystem and said master storage subsystem comprises a means of deciding said oldest time out of own latest time and acquired latest time.  
   
   
       6 . A storage subsystem as claimed in  claim 1 , wherein a plurality of storage subsystems which operate in said local mode are structured to transfer the data to one of the storage subsystems belonging to the storage subsystem group which operates in said remote mode, and said one of the storage subsystems belonging to the storage subsystem group which operates in said remote mode comprises a means of selecting the latest time given to each of the storage subsystems which operates in said local mode and a means of deciding the oldest time among the selected latest times as the candidates of said oldest time.  
   
   
       7 . A storage subsystem as claimed in  claim 1 , wherein the storage device of said storage subsystems comprises a plurality of volumes and when a volume belonging to the storage subsystem which is the source of copying operating in said local mode and a volume belonging to the storage subsystem which is the destination of copying operating in said remote mode form a volume pair, the storage subsystem operating in said local mode comprises a means of controlling the start and stop of the data transmission to the storage subsystem operating in said remote mode for each of volume groups comprising one or more volume pairs.