Abstract: A memory system according to an embodiment of the present invention comprises: 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 corresponding 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 and linking these tables.

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.

Abstract: A memory system includes a controlling unit that configured to control data transfer between the first and the second memory. The controlling unit executes copy processing for, after reading out data stored in a first page of the second memory to the first memory, writing the data in a second page of the second memory, determines, when executing the copy processing, whether the error correction processing for the data read out from the first page is successful, stores, when the error correction processing is successful, corrected data in the first memory and writes the corrected data in the second page, and reads out, when the error correction processing is unsuccessful, the data from the first page to the first memory and writes the data not subjected to the error correction processing in the second page.

Abstract: A memory system includes a nonvolatile semiconductor memory having blocks, the block being data erasing unit; and a controller configured to execute; an update processing for; writing superseding data in a block, the superseding data being treated as valid data; and invalidating superseded data having the same logical address as the superseding data, the superseded data being treated as invalid data; and a compaction processing for; retrieving blocks having invalid data using a management table, the management table managing blocks in a linked list format for each number of valid data included in the block; selecting a compaction source block having at least one valid data from the retrieved blocks; copying a plurality of valid data included in the compaction source blocks into a compaction target block; invalidating the plurality of valid data in the compaction source blocks; and releasing the compaction source blocks in which all data are invalidated.

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 nonvolatile memory including a plurality of blocks as data erase units, a measuring unit which measures an erase time at which data of each block is erased, and a block controller which writes data supplied from at least an exterior into a first block which is set in a free state and whose erase time is oldest.

Abstract: A memory system includes a nonvolatile semiconductor memory having blocks, the block being data erasing unit; and a controller configured to execute; an update processing for; writing superseding data in a block, the superseding data being treated as valid data; and invalidating superseded data having the same logical address as the superseding data, the superseded data being treated as invalid data; and a compaction processing for; retrieving blocks having invalid data using a management table, the management table managing blocks in a linked list format for each number of valid data included in the block; selecting a compaction source block having at least one valid data from the retrieved blocks; copying a plurality of valid data included in the compaction source blocks into a compaction target block; invalidating the plurality of valid data in the compaction source blocks; and releasing the compaction source blocks in which all data are invalidated.

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: A method of controlling a nonvolatile semiconductor memory includes checking a first group at a first interval period, the first group including a plurality of blocks, and when a first block in the first group satisfies a first condition, assigning the first block to a second group. The method includes checking, at a second interval period, an error count of data stored in the second group, and when a second block in the second group satisfies a second condition, moving data stored in the second block to an erased block in which stored data is erased among the plurality of blocks.

Abstract: A memory system includes a nonvolatile memory including a plurality of blocks as data erase units, a measuring unit which measures an erase time at which data of each block is erased, and a block controller which writes data supplied from at least an exterior into a first block which is set in a free state and whose erase time is oldest.

Abstract: According to one embodiment, a memory system includes a nonvolatile semiconductor memory include a first area, and a second area smaller than the first area; and a controller configured to control data stored in the nonvolatile semiconductor memory, wherein the nonvolatile semiconductor memory is configured to store a first data accessible by a host command and to a second data inaccessible by the host command, and when receiving the host command, the controller writes the second data of the first area within the second area and initializes a first address information related the first data.

Abstract: A memory system includes a first, second and third storing area included in a volatile semiconductor memory, and a controller that allocates the storage area of the nonvolatile semiconductor memory to the second storing area and the third storing area in a logical block unit associated with one or more blocks. First and second management units respectively manage the second and third storing areas. The second management unit has a size larger than that of the first management unit. When flushing data from the first to the second or third storing areas, the controller collects, from at least one of the first, second and third storing areas, data other than the data to be flushed and controls the flushing of the data such that a total of the data is a natural number times as large as the block unit as much as possible.

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: A memory system includes: a cache memory, a nonvolatile semiconductor memory, and a controller. The controller includes a plurality of management tables that manage data stored in the cache memory and the nonvolatile semiconductor memory using a cluster unit and a track unit. The controller performs data flushing processing from the cache memory to the nonvolatile semiconductor memory when the number of track units registered in the cache memory exceeds a predetermined threshold. Data may be flushed to the nonvolatile memory in different size data units such as a cluster or a track. Data flushing processing may also be performed if a last free way is used when data writing processing is performed on the cache memory managed in a set associative system. The nonvolatile semiconductor memory can be a NAND flash memory.

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-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 nonvolatile memory including a plurality of blocks as data erase units, a measuring unit which measures an erase time at which data of each block is erased, and a block controller which writes data supplied from at least an exterior into a first block which is set in a free state and whose erase time is oldest.

Abstract: A memory system includes a nonvolatile memory including a plurality of blocks as data erase units, a measuring unit which measures an erase time at which data of each block is erased, and a block controller which writes data supplied from at least an exterior into a first block which is set in a free state and whose erase time is oldest.

Abstract: A method of controlling a nonvolatile semiconductor memory includes checking a first group at a first interval period, the first group including a plurality of blocks, and when a first block in the first group satisfies a first condition, assigning the first block to a second group. The method includes checking, at a second interval period, an error count of data stored in the second group, and when a second block in the second group satisfies a second condition, moving data stored in the second block to an erased block in which stored data is erased among the plurality of blocks.

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.