Data routing and memory block management in a sub-block memory system

A data storage device, comprising:

• at least one controller;
• and
• a sub-block management system associated with the at least one controller and operable to:
• select a memory block for a relocation operation, the memory block being part of a pool of memory blocks that have been identified as candidates for the relocation operation;
• determine a first validity count associated with a first sub-block of the memory block;
• determine a second validity count associated with a second sub-block of the memory block;
• determine a difference between the first validity count and the second validity count;
• and
• perform the relocation operation on one of the first sub-block and the second sub-block when a difference between the first validity count and the second validity count exceeds a validity count difference threshold.

A data storage device, comprising:

• means for selecting a memory block from a pool of memory blocks for a garbage collection operation;
• means for determining a first validity count associated with a first sub-block of the memory block;
• means for determining a second validity count associated with a second sub-block of the memory block;
• means for determining a difference between the first validity count and the second validity count;
• and
• means for performing the garbage collection operation on the first sub-block and the second sub-block when a difference between the first validity count and the second validity count is within a validity count difference threshold.