Remote copy control method, storage sub-system with the method, and large area data storage system using them

Abstract

Two data centers located in the vicinity are connected using a synchronous transfer copy function, and one of the data centers is coupled with a third data center disposed at a remote location by an asynchronous remote copying function. The order whereat a storage sub-system located in the vicinity has received data from a host is consistently guaranteed, and the third data center holds the data. Further, each storage sub-system includes a function whereby, during normal operation, data can be exchanged and the data update state can be obtained by the storage sub-systems located in the two data centers that do not directly engage in data transmission.

1 . A remote copy control method for a storage sub-system comprising a control memory for storing control data, a cache memory for temporarily storing data, a microprocessor for controlling said control memory and said cache memory, a plurality of synchronous data destinations for synchronously receiving data from said microprocessor, and a plurality of asynchronous data destinations for asynchronously receiving data from said microprocessor, said remote copy control method comprising: 
 a first step of storing, in said control memory, information representative of transfer states/bit maps corresponding to said plurality of synchronous data destinations and information representative of transfer states/bit maps corresponding to said plurality of data destinations for asynchronously receiving;    a second step of another storage sub-system, which includes a transfer state/bit map that corresponds to one of said transfer states/bit maps, issuing to a storage sub-system that does not directly perform data transmission a command for transmitting an inquiry for a data update process state; and    a third step of, upon receiving a response to said command at said second step, updating said transfer states/bit maps.    
     
     
         2 . A remote copy control method according to  claim 1 , wherein the updating of said transfer states/bit maps at said third step includes the updating of a counter value that is included in said command for transmitting an inquiry for said data update process state, and that is used to count the times data in one part of a data block are updated.  
     
     
         3 . A storage sub-system, which includes a control memory for storing control data, a cache memory for temporarily storing data, a microprocessor for controlling said control memory and said cache memory, a first data destination for synchronously receiving said data from said microprocessor and a second data destination for asynchronously receiving said data from said microprocessor, comprising: 
 a function for issuing an inquiry for a data update process state of another storage sub-system that does not directly relate to data transmission.    
     
     
         4 . A storage sub-system according to  claim 3 , wherein one transfer state/bit map set is held by said storage sub-system and another storage sub-system that does not directly perform data transmission, and wherein said transfer bit/bit map set is updated by said function for transmitting an inquiry for a data update process state.  
     
     
         5 . A storage sub-system according to  claim 4 , wherein said transfer state/bit map set has an area for holding a counter value that represents the times data in one part of a data block is updated.  
     
     
         6 . A storage sub-system according to  claim 1 , wherein data transmission with said asynchronous data destinations is adaptive.  
     
     
         7 . A remote copy control method according to  claim 6 , wherein the updating of said transfer states/bit maps at said third step includes the updating of a counter value that is included in said command for transmitting an inquiry for said data update process state, and that is used to count the times data in one part of a data block are updated.