Memory system

Abstract

A memory system includes a volatile first storing unit, a nonvolatile second storing unit in which data is managed in a predetermined unit, and a controller that writes data requested by a host apparatus in the second storing unit via the first storing unit and reads out data requested by the host apparatus from the second storing unit to the first storing unit and transfers the data to the host apparatus. The controller includes a management table for managing the number of failure areas in a predetermined unit that occur in the second storing unit and switches, according to the number of failure areas, an operation mode in writing data in the second storing unit from the host apparatus.

1 - 19 . (canceled) 
     
     
         20 . A memory system comprising:
 a nonvolatile memory including a plurality of blocks; and   a controller configured to:
 refer to a number of free blocks in the nonvolatile memory; 
 determine whether the memory system has reached an end of its lifespan, wherein, 
 in a case that the controller determines that the memory system has reached the end of its lifespan, a data write operation to the nonvolatile memory becomes prohibited, and 
 after external power supply is restarted and the memory system is turned on and before the controller processes a new write command from a host, the controller controls the nonvolatile memory so that the data write operation to the nonvolatile memory becomes prohibited. 
   
     
     
         21 . The memory system according to  claim 20 , wherein
 the controller generates free blocks by controlling the nonvolatile memory, and   the controller stores a value that indicates a number of free blocks available in the nonvolatile memory.   
     
     
         22 . The memory system according to  claim 20 , wherein
 the controller stores a value that indicates a number of bad blocks in the nonvolatile memory.   
     
     
         23 . The memory system according to  claim 20 , wherein,
 after the data write operation to the nonvolatile memory is prohibited, the controller returns a notice indicating an error, without processing a data write request.   
     
     
         24 . The memory system according to  claim 20 , wherein,
 after the data write operation to the nonvolatile memory is prohibited, the controller performs error processing, without receiving a data write request.   
     
     
         25 . The memory system according to  claim 20 , wherein
 the nonvolatile memory is a NAND-type flash memory, and   the memory system is an SSD.   
     
     
         26 . The memory system according to  claim 26 , wherein
 the controller performs writing and readout of data in units of physical page size in the NAND-type flash memory.   
     
     
         27 . The memory system according to  claim 26 , wherein
 a size of an error correction code, which is added to main data, is not included in the physical page size.   
     
     
         28 . The memory system according to  claim 26 , wherein
 the physical page size is 4 kB, and   a redundant bit and data of which a size is a natural number multiple of 4 kB are simultaneously written in the nonvolatile memory.   
     
     
         29 . The memory system according to  claim 26 , wherein
 units of writing and readout set in the memory system is a logical page, and   the logical page is associated with one or more physical pages.   
     
     
         30 . The memory system according to  claim 29 , wherein
 a physical block includes a plurality of the physical pages, and   the controller performs erasure of data in units of physical block size in the NAND-type flash memory.   
     
     
         31 . The memory system according to  claim 30 , wherein
 a size of an error correction code, which is added to main data, is not included in the physical block size.   
     
     
         32 . The memory system according to  claim 30 , wherein
 the physical block size is 512 kB, and   a redundant bit and data of which a size is a natural number multiple of 512 kB are simultaneously erased from the nonvolatile memory.   
     
     
         33 . The memory system according to  claim 25 , wherein
 units of erasure set in the memory system is a logical block, and   the logical block is associated with one or more physical blocks.   
     
     
         34 . The memory system according to  claim 25 , wherein
 the controller manages data in units of a sector, a cluster, or a track,   the sector is a minimum access unit from the host,   a cluster size is equal to or larger than a sector size,   a logical page size is twice or larger natural number times as large as the cluster size,   a track size is twice or larger natural number times as large as the cluster size, and   a logical block size is twice or larger natural number times as large as the track size.   
     
     
         35 . The memory system according to  claim 25 , wherein
 the plurality of blocks includes a free block or a bad block,   the free block is a logical block on the NAND-type flash memory for which a use is not allocated, and, when a use is allocated to the free block, the free block is used after being erased, and   the bad block is a physical block on the NAND-type flash memory that cannot be used as a storage area because of a large number of errors, and the bad block is a physical block for which an erasing operation is not normally finished.   
     
     
         36 . The memory system according to  claim 25 , wherein
 the controller performs data transfer processing between a DRAM and the host in cooperation with a data managing unit via a DRAM controller,   the DRAM controller controls the DRAM, and   the data managing unit controls data transfer processing between the NAND-type flash memory and the DRAM.   
     
     
         37 . The memory system according to  claim 25 , wherein
 a write cache and a read cache are interposed between the host and the NAND-type flash memory, and   the write cache and the read cache are configured on a DRAM.   
     
     
         38 . A memory system comprising:
 a nonvolatile memory including a plurality of blocks; and   a controller configured to issue warning information based on a usage status of the nonvolatile memory, wherein   in a case that the controller determines that the memory system has reached an end of its lifespan, a data write operation to the nonvolatile memory becomes prohibited, and,   after the data write operation to the nonvolatile memory is prohibited and the memory system is restarted, the controller controls the nonvolatile memory to the data write operation to the nonvolatile memory becomes prohibited, and then the controller processes a new write command from a host.   
     
     
         39 . The memory system according to  claim 38 , wherein
 the controller generates free blocks by controlling the nonvolatile memory, and   the controller stores a value that indicates a number of free blocks available in the nonvolatile memory.   
     
     
         40 . The memory system according to  claim 38 , wherein
 the controller stores a value that indicates a number of bad blocks in the nonvolatile memory.   
     
     
         41 . The memory system according to  claim 38  wherein,
 after the data write operation to the nonvolatile memory is prohibited, the controller returns a notice indicating an error, without processing a data write request. 
 
     
     
         42 . The memory system according to  claim 38 , wherein,
 after the data write operation to the nonvolatile memory is prohibited, the controller performs error processing, without receiving a data write request.   
     
     
         43 . The memory system according to  claim 38 , wherein
 the nonvolatile memory is a NAND-type flash memory, and   the memory system is an SSD.   
     
     
         44 . The memory system according to  claim 38 , wherein
 the controller performs writing and readout of data in units of physical page size in the NAND-type flash memory.   
     
     
         45 . The memory system according to  claim 44 , wherein
 a size of an error correction code, which is added to main data, is not included in the physical page size.   
     
     
         46 . The memory system according to  claim 44 , wherein
 the physical page size is 4 kB, and   a redundant bit and data of which a size is a natural number multiple of 4 kB are simultaneously written in the nonvolatile memory.   
     
     
         47 . The memory system according to  claim 43 , wherein
 units of writing and readout set in the memory system is a logical page, and   the logical page is associated with one or more physical pages.   
     
     
         48 . The memory system according to  claim 47 , wherein
 a physical block includes a plurality of the physical pages, and   the controller performs erasure of data in units of physical block size in the NAND-type flash memory.   
     
     
         49 . The memory system according to  claim 48 , wherein
 a size of an error correction code, which is added to main data, is not included in the physical block size.   
     
     
         50 . The memory system according to  claim 48 , wherein
 the physical block size is 512 kB, and   a redundant bit and data of which a size is a natural number multiple of 512 kB are simultaneously erased from the nonvolatile memory.   
     
     
         51 . The memory system according to  claim 43 , wherein
 units of erasure set in the memory system is a logical block, and   the logical block is associated with one or more physical blocks.   
     
     
         52 . The memory system according to  claim 43 , wherein
 the controller manages data in units of a sector, a cluster, or a track,   the sector is a minimum access unit from the host,   a cluster size is equal to or larger than a sector size,   a logical page size is twice or larger natural number times as large as the cluster size,   a track size is twice or larger natural number times as large as the cluster size, and   a logical block size is twice or larger natural number times as large as the track size.   
     
     
         53 . The memory system according to  claim 43 , wherein
 the plurality of blocks includes a free block or a bad block,   the free block is a logical block on the NAND-type flash memory for which a use is not allocated, and, when a use is allocated to the free block, the free block is used after being erased, and   the bad block is a physical block on the NAND-type flash memory that cannot be used as a storage area because of a large number of errors, and the bad block is a physical block for which an erasing operation is not normally finished.   
     
     
         54 . The memory system according to  claim 43 , wherein
 the controller performs data transfer processing between a DRAM and the host in cooperation with a data managing unit via a DRAM controller,   the DRAM controller controls the DRAM, and   the data managing unit controls data transfer processing between the NAND-type flash memory and the DRAM.   
     
     
         55 . The memory system according to  claim 43 , wherein
 a write cache and a read cache are interposed between the host and the NAND-type flash memory, and   the write cache and the read cache are configured on a DRAM.   
     
     
         56 . A memory system comprising:
 a nonvolatile memory including a plurality of blocks; and   a controller configured to:
 refer to a number of free blocks in the nonvolatile memory; and 
 determine whether the memory system has reached an end of its lifespan, wherein, 
 in a case that the controller determines that the memory system has reached the end of its lifespan, a data write operation mode is changed, and, 
 after external power supply is restarted and the memory system is turned on and before the controller processes a new write command from a host, the controller controls the nonvolatile memory to be the data write operation mode becomes changed. 
   
     
     
         57 . The memory system according to  claim 56 , wherein
 the data write operation mode is changed to a write through mode, a read only mode, or a protection mode.   
     
     
         58 . A memory system comprising:
 a nonvolatile memory including a plurality of blocks; and   a controller configured to:
 refer to a number of free blocks in the nonvolatile memory; and 
 determine whether the memory system has reached an end of its lifespan, wherein, 
 in a case that the controller determines that the memory system has reached the end of its lifespan, a data write operation mode is changed to a read only mode, and, 
 in a case that a power supply is turned on after the data write operation mode is changed to the read only mode, the controller starts in the read only mode. 
   
     
     
         59 . The memory system according to  claim 58 , wherein,
 once the data write operation mode is changed to the read only mode, the controller continues processing in the read only mode until a reset or until the power supply is turned off.   
     
     
         60 . The memory system according to  claim 58 , wherein,
 during a task startup, the controller restores a state immediately before the power supply had been turned off.   
     
     
         61 . A memory system comprising:
 a nonvolatile memory in which data is erased in units of a block; and   a controller, wherein,   in a case that a power supply is turned on after a data write operation mode is changed to a read only mode, the controller starts in the read only mode.