Patent ID: 7613871
Filing Date: 2009-11-03
Classification: G06F,G11C

Abstract:
1. A storage system, comprising: a nonvolatile memory which erases data for respective blocks; and a controller for inputting and outputting the data to and from the nonvolatile memory, wherein the controller assigns at least one of the blocks in the nonvolatile memory as a rewritable area where stored data can be erased, and assigns at least a portion of the rest of the blocks in the non-volatile memory as a write once area where the stored data cannot be erased; wherein the controller determines a block belonging to the rewritable area based on an attribute of the block, and performs a wear leveling process and a reclamation process only on the block determined as belonging to the rewritable area, wherein the block stores retention period information of the stored data, wherein the storage system has a storage area including: the rewritable area where the stored data can be erased; the write-once area where the stored data cannot be erased; and an unused area for which the attribute is not determined; and wherein the controller erases data whose retention period expires from the block that stores the data, and changes the write-once area to the unused area by changing the attribute of the block.