Abstract: A method of controlling a nonvolatile semiconductor memory including a plurality of blocks, each one of the plurality of blocks being a unit of data erasing, includes determining a monitored block as a candidate for refresh operation from among the plurality of blocks based on a predetermined condition. The method includes monitoring an error count of data stored in the monitored block and not monitoring an error count of data stored in blocks excluding the monitored block among the plurality of blocks. The method also includes performing the refresh operation on data stored in the monitored block in which the error count is larger than a first threshold value.

Abstract: A memory system includes a volatile first storing unit, a nonvolatile second storing unit, and a controller. The controller performs data transfer, stores management information including a storage position of data stored in the second storing unit into the first storing unit, and performs data management while updating the management information. The second storing unit stores management information in a latest state and a storage position of the management information. The storage position information is read by the controller during a startup operation of the memory system and includes a second pointer indicating a storage position of the management information in a latest state and a first pointer indicating a storage position of the second pointer. The first pointer is stored in a fixed area in the second storing unit and the second pointer is stored in an area excluding the fixed area in the second storing unit.

Abstract: A memory system in which speed of processing for searching through management tables is increased by providing a forward lookup table for searching for, respectively in track and cluster units, from a logical address, a storage device position where data corresponds to the logical address, and a reverse lookup table for searching for, from a position of the storage device, a logical address stored in the position. These forward and reverse lookup tables are linked.

Abstract: A memory system according to an embodiment of the present invention comprises: a memory amount required for management table creation is reduced by adopting a nonvolatile semiconductor memory including a plurality of parallel operation elements respectively having a plurality of physical blocks as units of data erasing and a controller that can drive the parallel operation elements in parallel and has a number-of-times-of-erasing managing unit that manages the number of times of erasing in logical block units associated with a plurality of physical blocks driven in parallel.

Abstract: A memory system includes a management-information restoring unit. The management-information restoring unit determines whether a short break has occurred referring to a pre-log or a post-log in a NAND memory. The management-information restoring unit determines that a short break has occurred when the pre-log or the post-log is present in the NAND memory. In that case, the management-information restoring unit determines timing of occurrence of the short break, and, after selecting a pre-log or a post-log used for restoration, performs restoration of the management information reflecting these logs on a snapshot. Thereafter, the management-information restoring unit applies recovery processing to all write-once blocks in the NAND memory, takes the snapshot again, and opens the snapshot and the logs in the past.

Abstract: A memory system includes a volatile first storing unit, a nonvolatile second storing unit, and a controller. The controller performs data transfer, stores management information including a storage position of the data stored in the second storing unit into the first storing unit, and performs data management while updating the management information. The second storing unit has a management information storage area for storing management information storage information including management information in a latest state and a storage position of the management information. The storage position information is read by the controller during a startup operation of the memory system and includes a second pointer indicating a storage position of management information in a latest state in the management information storage area and a first pointer indicating a storage position of the second pointer.

Abstract: According to one embodiment, a disk array control device manages a plurality of drives as a single logical drive. The disk array control device includes a first register configured to store a to-be-accessed drive number which is designated by a host, and a control module. The control module is configured to receive a command from the host, determine whether the received command is a predetermined command which is used for maintenance of each of the drives, and execute, in a case where the received command is the predetermined command, a pass-through process of sending the received command to the drive which is designated by the to-be-accessed drive number in the first register.

Abstract: A controller includes an identification information management table that manages identification information indicating, for each of addresses in second-management unit, whether one or more data in first management unit belonging to the addresses is stored in the second or the third storing area. When the controller executes a process of flushing data from the first storing area to the second storing area or the third storing area, the controller updates the identification information in the identification information management table. The controller executes a process of reading data from the second storing area or the third storing area by referring to the identification information. As a result, the speed of searches conducted in the management table is increased.

Abstract: A memory system includes a management table group in which management information including storage positions of data stored in a first storing area and a second storing area is stored. The management table group is stored in the second storing area. A controller performs data transfer between a host apparatus and the second storing area via the first storing area and performs management of the data in the first and second storing areas based on the management table group while updating the management table group expanded in the first storing area. The second storing area can store data associated with a first logical address area accessible from the host apparatus and data associated with a second logical address area accessible from the host apparatus, and the controller receives an erasing command from the host apparatus, collects the data associated with the second logical address area in a predetermined area in the second storing area, and then initializes the management table group.

Abstract: A memory system includes a nonvolatile memory including a plurality of blocks, a volatile memory storing management information including a storage position of data stored in the nonvolatile memory, a management information writing unit, and a management information storing unit. The management information writing unit is configured to update, when the storage position of data is changed in the nonvolatile memory, the management information stored in the volatile memory. The management information storing unit is configured to, before writing data to the nonvolatile memory, store a first log including an update schedule of the management information in the nonvolatile memory and, after writing data to the nonvolatile memory, store a second log including an update result of the management information in the nonvolatile memory, wherein the management information storing unit is configured to store the first log and the second log in the same-numbered page of the different two blocks.

Abstract: A memory system includes a controller that manages data stored in the first and second storing areas. The controller determines, when a readout error occurs when the stored data in the second storing area is read out, success or failure of error correction to the read-out data based on the result of the error correction stored in a storage buffer, writes, when the error correction is successful, correction data corresponding to the read-out data stored in the storage buffer, and writes, when the error correction fails, the read-out data itself not subjected to error correction processing.

Abstract: A method of controlling a nonvolatile semiconductor memory including a plurality of blocks, each one of the plurality of blocks being a unit of data erasing, includes determining a monitored block as a candidate for refresh operation from among the plurality of blocks based on a predetermined condition. The method includes monitoring an error count of data stored in the monitored block and not monitoring an error count of data stored in blocks excluding the monitored block among the plurality of blocks. The method also includes performing the refresh operation on data stored in the monitored block in which the error count is larger than a first threshold value.

Abstract: A memory system includes a controller that reads out, data written in a nonvolatile second storing area, from which data is read out and in which data is written in a page unit, to a first storing area as a cache memory included in a semiconductor memory and transfers the data to the host apparatus. The controller performs, when a readout request from the host apparatus satisfies a predetermined condition, at least one of first pre-fetch for reading out, to the first storing area data from a terminal end of a logical address range designated by a readout request being currently processed to a boundary of a logical address aligned in the page unit and a second pre-fetch for reading out data from the boundary of the logical address aligned in the page unit to a next boundary of the logical address.

Abstract: As a semiconductor storage device that can efficiently perform a refresh operation, provided is a semiconductor storage device comprising a non-volatile semiconductor memory storing data in blocks, the block being a unit of data erasing, and a controlling unit monitoring an error count of data stored in a monitored block selected from the blocks and refreshing data in the monitored block in which the error count is equal to or larger than a threshold value.

Abstract: A memory system according to an embodiment of the present invention comprises: a data managing unit 120 is divided into a DRAM-layer managing unit 120a, a logical-NAND-layer managing unit 120b, and a physical-NAND-layer managing unit 120c to independently perform management of a DRAM layer, a logical NAND layer, and a physical NAND layer using the respective managing units to thereby perform efficient block management.

Abstract: A memory system includes a volatile first storing unit, a nonvolatile second storing unit in which a plurality of memory cells that can store multi-value data are arranged, the memory cells having a plurality of pages, and a controller that performs data transfer between a host apparatus and the second storing unit via the first storing unit. The controller includes a save processing unit that backs up, when, before data is written in the second storing unit in a write-once manner, data is written in a lower order page of a memory cell same as that of a page in which the data is written, the data of the lower order page and a broken-information-restoration processing unit that restores, when the data in the lower order page is broken, the broken data using the backed-up data.

Abstract: A memory system according to an embodiment of the present invention comprises: a data managing unit 120 is divided into a DRAM-layer managing unit 120a, a logical-NAND-layer managing unit 120b, and a physical-NAND-layer managing unit 120c to independently perform management of a DRAM layer, a logical NAND layer, and a physical NAND layer using the respective managing units to thereby perform efficient block management.

Abstract: A controller executes first processing for writing a plurality of data in a sector unit in the first storing area; second processing for flushing the data stored in the first storing area to the first input buffer in a first management unit twice or larger natural number times as large as the sector unit; third processing for flushing the data stored in the first storing area to the second input buffer in a second management unit twice or larger natural number times as large as the first management unit; fourth processing for relocating a logical block in which all pages are written in the first input buffer to the second storing area; fifth processing for relocating a logical block in which all pages are written in the second input buffer to the third storing area; and sixth processing for flushing a plurality of data stored in the second storing area to the second input buffer in the second management unit.

Abstract: A memory system includes a DRAM 20 that performs writing and readout in a unit equal to or smaller than a cluster, a NAND memory 10 that performs writing and readout in a page unit, and a management table group in which management information including storage locations of data stored in the DRAM 20 and the NAND memory 10 is stored. When a readout request is received from the outside, a data managing unit 120 notifies, when an unwritten logical address area is present in a storage area of the NAND memory to which a logical address area requested to be read out is mapped, fixed data stored in the DRAM 20 to the outside in association with the logical address area.

Abstract: As a semiconductor storage device that can efficiently perform a refresh operation, provided is a semiconductor storage device comprising a non-volatile semiconductor memory storing data in blocks, the block being a unit of data erasing, and a controlling unit monitoring an error count of data stored in a monitored block selected from the blocks and refreshing data in the monitored block in which the error count is equal to or larger than a threshold value.