Storage system

Abstract

According to one embodiment, a storage system includes a first storage including first nonvolatile memories storing data which is corrupted when data is read from the first nonvolatile memories, and a controller which controls the first storage. The controller reads data from a first nonvolatile memory at a first address, and determines that whether the read data is to be written back to the first storage or not.

What is claimed is: 
     
         1 . A storage system comprising:
 a first storage which includes first nonvolatile memories storing data which is to be corrupted when data is read from the first nonvolatile memories; and   a second storage which includes second nonvolatile memories storing data in a nonvolatile manner; and   a controller which controls the first and second storages,   wherein the controller is configured to:   read data from a first nonvolatile memory at a first address;   determine whether the read data is to be written back to the first storage or not;   write the read data to a second nonvolatile memory at a second address in the second storage, if it is determined that the read data is not to be written back to the first storage; and   write the read data to a first nonvolatile memory at a third address in the first storage, if it is determined that the read data is to be written back to the first storage.   
     
     
         2 . The storage system of  claim 1 , wherein the controller is configured to determine whether the read data is to be written back to the first storage or not, based on the number of data writes to the first nonvolatile memory at the first address. 
     
     
         3 . The storage system of  claim 1 , further comprising a third storage which stores data in a nonvolatile manner, and is larger than the second storage in at least data capacity. 
     
     
         4 . The storage system of  claim 1 , further comprising an address conversion table which indicates the correspondence between logical addresses managed by a host and physical addresses managed by the storage system. 
     
     
         5 . The storage system of  claim 4 , wherein the controller updates the address conversion table after writing the read data to the second nonvolatile memory at the second address of the second storage. 
     
     
         6 . The storage system of  claim 5 , wherein in the address conversion table, the controller updates a first physical address corresponding to the first address to a second physical address corresponding to the second address. 
     
     
         7 . The storage system of  claim 4 , wherein the controller updates the address conversion table after writing the read data to the first nonvolatile memory at the third address of the first storage. 
     
     
         8 . The storage system of  claim 7 , wherein in the address conversion table, the controller updates a first physical address corresponding to the first address to a third physical address corresponding to the third address. 
     
     
         9 . The storage system of  claim 1 , wherein the first nonvolatile memory includes:
 a resistance change element including a resistance value which varies in accordance with a flowing direction of current in the resistance change element; and   a switching element which switches the flowing direction of the current in the resistance change element.   
     
     
         10 . The storage system of  claim 9 , wherein the resistance change element includes:
 a free layer including a magnetization direction which varies in accordance with the flowing direction of current in the free layer;   a pinned layer including a fixed magnetization direction; and   a tunnel insulating film provided between the free layer and the pinned layer.   
     
     
         11 . The storage system of  claim 1 , wherein the first storage is an MRAM. 
     
     
         12 . The storage system of  claim 1 , wherein the second storage is a NAND flash memory. 
     
     
         13 . The storage system of  claim 3 , wherein the third storage is an HDD. 
     
     
         14 . A storage system comprising:
 a first storage including first nonvolatile memories storing data which is to be corrupted when data is read from the first nonvolatile memories; and   a controller which controls the first storage,   wherein the controller is configured to:   read data from a first nonvolatile memory at a first address;   determine whether the read data is to be rewritten to the first storage or not; and   write the read data to a first nonvolatile memory at a second address in the first storage, if it is determined that the read data is to be rewritten to the first storage.