Storage system, storage device, and remote copy method

Abstract

A first data transfer module sends update data to be written into a primary volume to a second data transfer module; the second data transfer module stores the update data into a secondary volume, stores differential data written to a storage address for the update data in the secondary volume into a second differential volume, updates a second management information holding module, and then informs completion of the data updating to the first data transfer module; and the first data transfer module stores the update data to an update address in the primary volume when the information of completion of the data updating is received from the second data transfer module, stores the differential data into a first differential volume, and updates a first management information holding module.

1 . (canceled)  
   
   
       2 . A storage system, comprising a primary disk subsystem having a disk drive provided for normal operation, a secondary disk subsystem having a disk drive that stores a duplicate of data stored in the primary disk subsystem, and a communications line that connects the primary disk subsystem and the secondary disk subsystem, 
 the primary disk subsystem comprising a primary volume where normal reading and writing are performed, a first differential volume that stores differential data of a snapshot of the primary volume, a first management information holding module that manages the differential data, and a first data transfer module that transfers data to the secondary disk subsystem,    the secondary disk subsystem comprising a secondary volume that stores a duplicate of the data stored in the primary volume, a second differential volume that stores differential data of a snapshot of the secondary volume, a second management information holding module that manages the differential data, and a second data transfer module that transfers data to the primary disk subsystem,    wherein:    the first data transfer module sends update data to be written into the primary volume to the second data transfer module;    the second data transfer module:    stores the update data in the secondary volume;    stores the differential data stored at the update address in the secondary volume, into the second differential volume;    updates the second management information holding module; and    then informs completion of data updating to the first data transfer module; and    the first data transfer module:    when the information of completion of the data updating is received from the second data transfer module;    stores the update data to the update address in the primary volume;    stores the differential data stored at the update address in the primary volume, into the first differential volume; and    updates the first management information holding module.    
   
   
       3 .- 6 . (canceled)  
   
   
       7 . The storage system according to  claim 2 , wherein: 
 the first data transfer module sends the update data to be written into the primary volume, and the update address where the update data is to be written, to the second data transfer module; and    the second data transfer module:    reads the differential data stored in the update address in the secondary volume and stores the differential data into the second differential volume;    stores the update data sent from the first data transfer module to the update address in the secondary volume;    updates the second management information holding module based on the storage address where the differential data is to be stored into the second differential volume; and    then informs the completion of the data updating to the first data transfer module.    
   
   
       8 . A storage device used in a storage system comprising a primary storage device having a disk drive provided for normal operation, a secondary storage device having a disk drive that stores a duplicate of data stored in the primary storage device, and a communications line that connects the primary storage device and the secondary storage device, 
 the primary storage device comprising a primary volume where normal reading and writing are performed, a first differential volume that stores differential data of a snapshot of the primary volume, a first management information holding module that manages the differential data, and a first data transfer module that transfers data to the secondary storage device,    the secondary storage device comprising a secondary volume that stores a duplicate of the data stored in the primary volume, a second differential volume that stores differential data of a snapshot of the secondary volume, a second management information holding module that manages the differential data, and a second data transfer module that transfers data to the primary storage device,    wherein the first data transfer module:    sends the update data to be written into the primary volume to the second data transfer module;    stores the update data to the update address in the primary volume when information of completion is received from the second data transfer module;    stores the differential data into the first differential volume; and    updates the first management information holding module.    
   
   
       9 .- 11 . (canceled)  
   
   
       12 . A storage device used by a storage system comprising a primary storage device having a disk drive provided for normal operation, a secondary storage device having a disk drive that stores a duplicate of data stored in the primary storage device, and a communications line that connects the primary storage device and the secondary storage device, 
 the primary storage device comprising a primary volume where normal reading and writing are performed, a first differential volume that stores differential data of a snapshot of the primary volume, a first management information holding module that manages the differential data, and a first data transfer module that transfers data to the secondary storage device,    the secondary storage device comprising a secondary volume that stores a duplicate of the data stored in the primary volume, a second differential volume that stores differential data of a snapshot of the secondary volume, a second management information holding module that manages the differential data, and a second data transfer module that transfers data to the primary storage device,    wherein the second data transfer module:    receives the update data sent from the first data transfer module to be written into the secondary volume;    stores the update data into the secondary volume;    stores the differential data stored at the update address in the secondary volume, into the second differential volume;    updates the second management information holding module; and    then informs completion of the data updating for updating data to the primary storage device.    
   
   
       13 .- 16 . (canceled)  
   
   
       17 . The storage device according to  claim 12 , wherein the second data transfer module: 
 receives from the first data transfer module the update data to be written into the primary volume and the update address where the update data is to be written;    reads the differential data stored in the update address in the secondary volume and stores the differential data into the second differential volume;    stores the received update data to the update address in the secondary volume;    updates the second management information holding module based on the storage address where the differential data is to be stored into the second differential volume; and    then informs the completion of the data updating to the first data transfer module.    
   
   
       18 . A remote copy method used in a storage system comprising a primary disk subsystem having a disk drive provided for normal operation, a secondary disk subsystem having a disk drive that stores a duplicate of data stored in the primary disk subsystem, and a communications line that connects the primary disk subsystem and the secondary disk subsystem, 
 the primary disk subsystem comprising a primary volume where normal reading and writing are performed, a first differential volume that stores differential data of a snapshot of the primary volume, a first management information holding module that manages the differential data, and a first data transfer module that transfers data to the secondary disk subsystem,    the secondary disk subsystem comprising a secondary volume that stores a duplicate of the data stored in the primary volume, a second differential volume that stores differential data of a snapshot of the secondary volume, a second management information holding module that manages the differential data, and a second data transfer module that transfers data to the primary disk subsystem,    the remote copy method comprising:    a first step of controlling the first data transfer module to send the update data to be written into the primary volume to the second data transfer module;    a second step of controlling the second data transfer module to:    store the update data sent from the first data transfer module into the secondary volume;    store the differential data written in the storage address where the update data is stored in the secondary volume, into the second differential volume;    update the second management information holding module; and    then inform the completion of data updating to the first data transfer module; and    a third step of controlling the first data transfer module to:    store the update data to the update address in the primary volume when a information of completion is received from the second data transfer module;    store the differential data into the first differential volume; and    update the first management information holding module.    
   
   
       19 .- 20 . (canceled)