System and method for improving wear-leveling performance in solid-state memory

A data storage subsystem capable of regulating a maximum number of wear leveling operations triggered by an erase operation, the data storage subsystem comprising:

• a non-volatile solid-state memory array comprising a plurality of groups of blocks, the blocks within each group of blocks distributed across different ones of a plurality of memory units in the non-volatile solid-state memory array;
• and
• a controller configured to:
• receive an erase command directed to a group of the plurality of groups of blocks;
• and
• determine whether to perform a wear leveling operation on at least one block in the group of blocks to which the erase command is directed, the determining based at least on (1) a number of erase commands already performed on individual blocks within the group, and (2) one or more individual wear leveling thresholds associated with memory units to which the blocks in the group are distributed,
• wherein an individual wear leveling threshold associated with at least some memory units differs from an individual wear leveling threshold associated with at least some other memory units, and
• wherein each of the individual wear leveling thresholds is based on (1) a position of the memory unit within the plurality of memory units and (2) an interval threshold denoting a minimum frequency at which a wear leveling operation is to be performed on a block.

A data storage subsystem capable of regulating a maximum number of wear leveling operations triggered by an erase operation, the data storage subsystem comprising:

• a non-volatile solid-state memory array comprising a plurality of groups of blocks, the blocks within each group of blocks distributed across different ones of a plurality of memory units in the non-volatile solid-state memory array;
• and
• a controller configured to:
• receive an erase command directed to a group of the plurality of groups of blocks;
• and
• determine whether to perform a wear leveling operation on at least one block in the group of blocks to which the erase command is directed, the determining based at least on (1) a number of erase commands already performed on individual blocks within the group, and (2) one or more individual wear leveling thresholds associated with memory units to which the blocks in the group are distributed,
• wherein an individual wear leveling threshold associated with at least some memory units differs from an individual wear leveling threshold associated with at least some other memory units, and
• wherein the individual wear leveling threshold associated with a memory unit is a sum of (1) a position number of the associated memory unit within the plurality of memory units and (2) an interval threshold denoting a minimum frequency at which a wear leveling operation is to be performed on a block.

A data storage subsystem capable of regulating a maximum number of wear leveling operations triggered by an erase operation, the data storage subsystem comprising:

• a non-volatile solid-state memory array comprising a plurality of groups of blocks, the blocks within each group of blocks distributed across different ones of a plurality of memory units in the non-volatile solid-state memory array;
• and
• a controller configured to:
• receive an erase command directed to a group of the plurality of groups of blocks;
• determine whether to perform a wear leveling operation on at least one block in the group of blocks to which the erase command is directed, the determining based at least on (1) a number of erase commands already performed on individual blocks within the group, and (2) one or more individual wear leveling thresholds associated with memory units to which the blocks in the group are distributed;
• for each of the blocks in group, perform a modulo operation with (1) a difference between the number of erase commands already on the block and the individual wear leveling threshold associated with the memory unit to which the block is assigned and (2) an interval threshold denoting a minimum frequency at which a wear leveling operation is to be performed on a block;
• and
• select the block for a wear leveling operation when the modulo operation results in a zero remainder,
• wherein an individual wear leveling threshold associated with at least some memory units differs from an individual wear leveling threshold associated with at least some other memory units.

A method for regulating a maximum number of wear leveling operations triggered by an erase operation in a non-volatile data storage subsystem comprising a plurality of groups of blocks, the blocks within each group of blocks distributed across different ones of a plurality of memory units in the non-volatile data storage subsystem, the method comprising:

• receiving an erase command directed to a group of the plurality of groups of blocks;
• and
• determining whether to perform a wear leveling operation on at least one block in the group of blocks to which the erase command is directed, the determining based at least on (1) a number of erase commands already performed on individual blocks within the group, and (2) one or more individual wear leveling thresholds associated with memory units to which the blocks in the group are distributed,
• wherein an individual wear leveling threshold associated with at least some memory units differs from an individual wear leveling threshold associated with at least some other memory units, and
• wherein each of the individual wear leveling thresholds is based on (1) a position of the memory unit within the plurality of memory units and (2) an interval threshold denoting a minimum frequency at which a wear leveling operation is to be performed on a block.

A method for regulating a maximum number of wear leveling operations triggered by an erase operation in a non-volatile data storage subsystem comprising a plurality of groups of blocks, the blocks within each group of blocks distributed across different ones of a plurality of memory units in the non-volatile data storage subsystem, the method comprising:

• receiving an erase command directed to a group of the plurality of groups of blocks;
• and
• determining whether to perform a wear leveling operation on at least one block in the group of blocks to which the erase command is directed, the determining based at least on (1) a number of erase commands already performed on individual blocks within the group, and (2) one or more individual wear leveling thresholds associated with memory units to which the blocks in the group are distributed,
• wherein an individual wear leveling threshold associated with at least some memory units differs from an individual wear leveling threshold associated with at least some other memory units, and
• wherein the individual wear leveling threshold associated with a memory unit is a sum of (1) a position number of the associated memory unit within the plurality of memory units and (2) an interval threshold denoting a minimum frequency at which a wear leveling operation is to be performed on a block.

A method for regulating a maximum number of wear leveling operations triggered by an erase operation in a non-volatile data storage subsystem comprising a plurality of groups of blocks, the blocks within each group of blocks distributed across different ones of a plurality of memory units in the non-volatile data storage subsystem, the method comprising:

• receiving an erase command directed to a group of the plurality of groups of blocks;
• determining whether to perform a wear leveling operation on at least one block in the group of blocks to which the erase command is directed, the determining based at least on (1) a number of erase commands already performed on individual blocks within the group, and (2) one or more individual wear leveling thresholds associated with memory units to which the blocks in the group are distributed;
• for each of the blocks in group, performing a modulo operation with (1) a difference between the number of erase commands already on the block and the individual wear leveling threshold associated with the memory unit to which the block is assigned and (2) an interval threshold denoting a minimum frequency at which a wear leveling operation is to be performed on a block;
• and
• selecting the block for a wear leveling operation when the modulo operation results in a zero remainder,
• wherein an individual wear leveling threshold associated with at least some memory units differs from an individual wear leveling threshold associated with at least some other memory units.