Storage system and data management method

Abstract

The present invention comprises a CHA 110 which transmits/receives data to/from an external device, a DKA 140 which transmits/receives data to/from an HDD unit 200 , a primary cache unit 120 which has a primary cache memory 124 , a secondary cache unit 130 which is installed between the primary cache unit 120 and the DKA 140 and has a secondary cache memory 134 , a CCP 121 which stores write target data received by the CHA 110 in the primary cache memory 124 , and a CCP 131 which stores the write target data in the secondary cache memory 134 , and transfers the write target data stored in the secondary cache memory 134 to the DKA 140.

1 . A storage system comprising:
 a storage controller,   a first volatile cache memory and a second volatile cache memory,   a first non-volatile cache memory and a second non-volatile cache memory, and   a plurality of disk drives,   wherein, the storage controller configured to:
 receive write request from a computer,
 store write data corresponding to the write request in the first volatile cache memory and the second volatile cache memory, and 
 store the write data, stored in the first volatile cache memory or the second volatile cache memory, in the first non-volatile cache memory and the second non-volatile cache memory, or store the write data stored in the fret volatile cache memory or the second. volatile cache memory, in the plurality of disk drives. 
 
   
     
     
         2 . A storage system according to  claim 1 , wherein
 the storage controller configured to receive read request from the computer:
 if read target data corresponding to the read request is stored in the first volatile cache memory, the read target data is provided from the first non-volatile cache memory to the computer, 
 if the read target data is not stored in the first volatile cache memory and stored in the first non-volatile cache memory, the read target data is provided from the first non-volatile cache memory to the computer via the first volatile cache memory, and 
 if the read target data is not stored in each of the first volatile cache memory and the first non-volatile cache memory, the read target data is provided from the plurality of disk drives to the computer via the first volatile cache memory. 
   
     
     
         3 . A storage system according to  claim 1 , wherein
 the storage controller is configured to send a completion notice to the computer after storing the write data in the first volatile cache memory and the second volatile cache memory.   
     
     
         4 . A storage system according to  claim 3 , wherein
 the storage controller is configured to delete the write data stored in the first volatile cache memory or the write data stored in the second volatile cache memory after storing the write data in the first non-volatile cache memory or the second non-volatile cache memory.   
     
     
         5 . A storage system according to  claim 1 , wherein the storage controller is configured to delete data from the first volatile cache memory after a first predetermined period of time has elapsed. 
     
     
         6 . A storage system according to  claim 5 , wherein the storage controller is configured to delete data from the first non-volatile cache memory after a second predetermined period of time has elapsed. 
     
     
         7 . A storage system according to  claim 6 , wherein the first predetermined period of time is shorter than the second predetermined period of time.