Abstract: According to one embodiment, a memory controller includes a writing destination management unit which determines a writing destination of user data, an encoding unit which generates a parity of the user data, and an ECC management unit which measures a fatigue degree of each certain memory area of a nonvolatile memory, selects an encoding method to instruct the encoding unit to be performed according to the encoding method, and changes the encoding method to an encoding method having a high error correction capability in a case where the fatigue degree corresponding to the writing destination is equal to or higher than a threshold and a total sum of parities is equal to or less than a predetermined amount.

Abstract: According to one embodiment, a memory device includes a memory unit including a first subunit and a second subunit, a code encoding unit configured to calculate first redundant data based on first write data and second redundant data based on second write data, and a control unit configured to cause the first write data and the first redundant data to be written in the first subunit and the second write data and the second redundant data to be written in the second subunit. The control unit is configured to control the code encoding unit to start calculation of the second redundant data after all of the writing steps for writing the first write data and the first redundant data have been carried out.

Abstract: According to one embodiment, a storage device includes an encoder, a nonvolatile memory that stores user data and a parity, a magnetic disk, and a management unit that holds correspondence between a logical address and a first physical address as first conversion information, and holds correspondence between the first physical address and a second physical address as second conversion information, with the second physical address including media information indicating a medium of a storage destination and information indicating a storage position. When the user data stored in the nonvolatile memory is to be moved to the magnetic disk, the management unit updates the second physical address of the user date in the second conversion information, to a value indicating a storage destination after the movement.

Abstract: According to one embodiment, a memory system includes a nonvolatile semiconductor memory device and a controller. The system includes the nonvolatile semiconductor memory device including a plurality of memory cells; and the controller configured to control one of read operation, write operation, and a use frequency of the read operation or the write operation on the nonvolatile semiconductor memory device, and configured to change controlling for a memory cell belonging to a first group of the memory cells and to change controlling for a memory cell belonging to a second group located on an upper side or a lower side of the memory cell belonging to the first group.

Abstract: A controller according to one embodiment controls a memory, the memory including blocks and configured to erase data in the blocks with each of the blocks as a minimum unit. Each of the blocks includes unit memory areas each specified by an address. The controller is configured to add a code for error correction to received data to generate a data unit, divide the data unit into data unit sections, and write the data unit sections in unit memory areas of respective blocks, the unit memory areas having different addresses.

Abstract: According to an embodiment, an access controller refers to state information upon an erase operation, causes the erase operation to be performed on all the collection of physical blocks included in a first logical block, and causes the erase operation to be performed on a part of the collection of physical blocks included in a second logical block and does not causes the erase operation to be performed on rest of the collection of the physical blocks in the second logical block.

Abstract: According to one embodiment, a memory system includes a bit-error-rate manager configured to manage information associated with a bit error rate for each physical block, a logical-block constructing unit configured to construct a logical block based on the information associated with the bit error rate, and a block manager configured to manage the correspondence between the logical block constructed by the logical-block constructing unit and the physical blocks. The logical block is a collection of a plurality of physical blocks.

Abstract: According to one embodiment, a memory system includes a non-volatile semiconductor memory, a block management unit, and a transcription unit. The semiconductor memory includes a plurality of blocks to which data can be written in both the first mode and the second mode. The block management unit manages a block that stores therein no valid data as a free block. When the number of free blocks managed by the block management unit is smaller than or equal to a predetermined threshold value, the transcription unit selects one or more used blocks that stores therein valid data as transcription source blocks and transcribes valid data stored in the transcription source blocks to free blocks in the second mode.

Abstract: According to one embodiment, a virtual block is constructed according to configuration conditions that, when a plurality of physical blocks included in the virtual block are selected, the sum of the number of physical block pairs and the number of single blocks allocated from the same memory chip to one virtual block is less than or equal to a first value.

Abstract: According to one embodiment, apparatus includes non-volatile memory chips, and a first controller which executes processing for reading first valid data stored in a first storage region of a first non-volatile memory chip in the non-volatile memory chips, processing for storing the first valid data in a buffer memory, processing for writing the first valid data stored in the buffer memory in a second storage region of the first non-volatile memory chip, and processing for erasing data stored in the first storage region. Each of the non-volatile memory chips comprises erase blocks. Each erase block includes write blocks. Each of the first storage region and the second storage region includes at least one erase block.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory including first blocks configured to store an address indicating a data storage position, and second blocks configured to store the data, a first table configured to store a first address including first information and second information, the second information indicating a data storage position in the first block, and a second table configured to convert the first information into third information, the first information having a first data size by which one entry of the second table can be identified, the third information having a second data size which is larger than the first data size and by which one of the first blocks and the second blocks can be identified.

Abstract: According to one embodiment, a memory system includes a plurality of non-volatile memory chips and a memory controller. The memory controller controls a read operation of the memory chips, and manages correspondence relation information between a logical address included in a read command and a physical address of the memory chip. The memory controller causes at least two memory chips to store the same correspondence relation information. Further, in the read operation, the memory controller reads the correspondence relation information from at least one memory chip among the plurality of memory chips storing the same correspondence relation information.

Abstract: According to one embodiment, a memory system includes a non-volatile semiconductor memory, a block management unit, and a transcription unit. The semiconductor memory includes a plurality of blocks to which data can be written in both the first mode and the second mode. The block management unit manages a block that stores therein no valid data as a free block. When the number of free blocks managed by the block management unit is smaller than or equal to a predetermined threshold value, the transcription unit selects one or more used blocks that stores therein valid data as transcription source blocks and transcribes valid data stored in the transcription source blocks to free blocks in the second mode.

Abstract: According to one embodiment, a memory device includes a memory unit including a first subunit and a second subunit, a code encoding unit configured to calculate first redundant data based on first write data and second redundant data based on second write data, and a control unit configured to cause the first write data and the first redundant data to be written in the first subunit and the second write data and the second redundant data to be written in the second subunit. The control unit is configured to control the code encoding unit to start calculation of the second redundant data after all of the writing steps for writing the first write data and the first redundant data have been carried out.

Abstract: According to one embodiment, a memory controller includes a first interface, a second interface, a cache unit, a translation unit, an access unit and a lock unit. The first interface receives a lock request and an access request which includes a logical address. The second interface is connectable to a non-volatile memory. The cache unit comprises a plurality of cache line and caches correspondence information between the logical address and a physical address of the non-volatile memory. The translation unit translates the logical address included in the access request into the physical address with reference to the cache unit. The access unit performs access in accordance with the access request to a position indicated by the translated physical address. The lock unit sets the cache line lock state in accordance with the lock request. The lock state is the state where the cache line being prohibited to be refilled.

Abstract: According to an embodiment, a retention time of each block group is managed and a degree of wear of each block is managed. A free block allocated to each block group is determined based on the retention time of each block group and the degree of wear of each block.

Abstract: According to one embodiment, a memory controller controlling a NAND memory having D bits/cell, includes: a code encoder which generates a code word having correction capability of t symbols; a write control unit which controls writing of the code word to the NAND memory; and a code decoder which decodes the code word read from the NAND memory, wherein the write control unit dispersedly allocates 2×D pages stored in adjacent two word lines in a block of the NAND memory to 2×D/t or more code words.

Abstract: According to one embodiment, a memory system includes a nonvolatile memory, a managing unit, an order rule holding unit, a position information storing unit, a list selecting unit, a block selecting unit, a writing unit, and an updating unit. The managing unit holds for each of storage areas of the nonvolatile memory a free block list indicating free blocks. The order rule holding unit holds an order rule used to determine an order of the free block lists. The position information storing unit stores position information indicating the position of the free block list in the order rule. The list selecting unit selects the free block list corresponding to the position indicated by the position information and the block selecting unit selects the free block therefrom. The updating unit updates after the list selection the position information in the position information storing unit with position information indicating the position of the subsequently selected free block list.

Abstract: According to the embodiments, a first management table, which is included in a nonvolatile second semiconductor memory and manages data included in a second storage area by a first management unit, is stored in the second semiconductor memory and a second management table for managing data in the second storage area by a second management unit larger than the first management unit is stored in a first semiconductor memory capable of random access.

Abstract: According to one embodiment, a controller controls writing into and reading from a storage apparatus that includes a first data-storage unit and a second data-storage unit. The second data-storage unit stores user data and parity data of the user data. The first data-storage unit stores the parity data. The controller includes a parity updating unit and a parity writing unit. When parity data is updated, the parity updating unit writes the updated parity data into the first data-storage unit. When a certain requirement is satisfied, the parity writing unit reads the parity data written in the first data-storage unit, and writes the parity data thus read into the second data-storage unit.