Nonvolatile semiconductor memory drive, information processing apparatus and management method of storage area in nonvolatile semiconductor memory drive

A nonvolatile semiconductor memory drive of a type in which data is additionally written, the memory drive comprising:

• a nonvolatile semiconductor memory arranged as a plurality of groups, each of the plurality of groups consisting of a plurality of pages, each of the plurality of pages comprising at least one cluster used as a data management unit;
• and
• a controller coupled to the semiconductor memory, the controller configured to control a process of writing and reading data with respect to the nonvolatile semiconductor memory, the controller comprising:
• a compaction module configured to acquire free groups by rearranging valid data scattered in n groups in groups of a number not larger than n−1 when the number of free groups remaining in a plurality of groups becomes not larger than a predetermined number, wherein the valid data being rearranged is in a unit of clusters, and
• a compression module configured to acquire free groups in order to suppress an execution opportunity of the compaction module, by compressing data stored in m groups in which access to valid data stored therein has not been made for a period longer than a predetermined period, and rearranging the compressed data in groups of a number not larger than m−1, wherein data being compressed is in a unit of groups, the compression module further decompresses the compressed data and rearranges the decompressed data when capacity of invalidated data in a group set in a state in which the stored data is compressed and rearranged together with stored data of another group exceeds a predetermined value.

An information processing apparatus comprising:

• a main body device;
• and
• a nonvolatile semiconductor memory drive of a type in which data is additionally written, the memory drive comprising a nonvolatile semiconductor memory arranged as a plurality of groups, each of the plurality of groups consisting of a plurality of pages, each of the plurality of pages comprising at least one cluster used as a data management unit,
• wherein the main body device comprises a data access request module configured to issue a data access request for the nonvolatile semiconductor memory to the nonvolatile semiconductor memory drive,
• wherein the nonvolatile semiconductor memory drive further comprises a controller coupled to the semiconductor memory, the controller configured to control a process of writing and reading data with respect to the nonvolatile semiconductor memory,
• wherein the controller of the nonvolatile semiconductor memory drive comprises:
• a compaction module configured to acquire free groups by rearranging valid data scattered in n groups in groups of a number not larger than n−1 when the number of free groups remaining in a plurality of groups becomes not larger than a predetermined number, wherein the valid data being rearranged is in a unit of clusters,
• a compression module configured to acquire free groups in order to suppress an execution opportunity of the compaction module, by compressing data stored in m groups in which access to valid data therein has not been made for a period longer than a predetermined period, and rearranging the compressed data in groups of a number not larger than m−1, wherein data being compressed is in a unit of groups,
• a control module configured to interrupt free group acquisition process by the compression module when a data access request for the nonvolatile semiconductor memory is issued from the main body device while the free group acquisition process by the compression module is being performed, and
• wherein the compression module decompresses the compressed data and rearranges the decompressed data when a read frequency with respect to valid data in a group set in a state in which the stored data is compressed and rearranged together with stored data of another group exceeds a predetermined number.

A management method of managing a storage area in a nonvolatile semiconductor memory drive of a type in which data is additionally written, the memory drive comprising a nonvolatile semiconductor memory arranged as a plurality of groups, each of the plurality of groups consisting of a plurality of pages, each of the plurality of pages comprising at least one cluster used as a data management unit, and a controller coupled to the semiconductor memory, the controller configured to control a process of writing and reading data with respect to the nonvolatile semiconductor memory, the method comprising:

• acquiring free groups by rearranging valid data stored in n groups in groups of a number not larger than n−1 when the number of free groups remaining in a plurality of groups becomes not larger than a predetermined number, wherein the valid data being rearranged is in a unit of clusters;
• and
• in order to suppress an execution opportunity of the acquiring of free groups by rearranging valid data, acquiring free groups by compressing data stored in m groups in which access to valid data stored therein has not been made for a period longer than a predetermined period and rearranging the compressed data in groups of a number not larger than m−1, wherein the data being compressed is in a unit of groups, and wherein
• the acquiring free groups by compressing data comprises decompressing the compressed data and rearranging the decompressed data when a read frequency with respect to valid data in a group set in a state in which the stored data is compressed and rearranged together with stored data of another group exceeds a predetermined number.