Adaptive health grading for a non-volatile memory

A data storage system, comprising:

• an integrated circuit implementing a controller configured to be coupled to a non-volatile memory array including a plurality of blocks of physical memory, wherein the controller is configured to:
• assign the plurality of blocks in the memory array to a plurality of different health grades by applying a set of health grade thresholds to block health metrics of the plurality of blocks;
• maintain a plurality of ready-to-use queues identifying blocks that do not currently hold valid data and are ready for use for data storage, where each of the plurality of ready-to-use queues is associated with a respective one of the plurality of health grades;
• monitor fill levels in the plurality of ready-to-use queues;
• adjust at least one health grade threshold in the set of health grade thresholds for the plurality of blocks based on the fill levels;
• and
• based on the adjustment of the at least one health grade threshold, thereafter re-grade blocks among the plurality of blocks in the ready-to-use queues with respect to the plurality of health grades and assign blocks among the plurality of blocks to the plurality of ready-to-use queues in accordance with the at least one health grade block threshold that was adjusted, such that distribution of blocks within the plurality of ready-to-use queues is improved.

A computer program product, the computer program product comprising a computer readable storage device having program instructions embodied therewith, the program instructions executable by a controller for a non-volatile memory array including a plurality of blocks of physical memory, to cause the controller to perform:

• assigning the plurality of blocks in the memory array to a plurality of different health grades by applying a set of health grade thresholds to block health metrics of the plurality of blocks;
• maintaining a plurality of ready-to-use queues identifying blocks that do not currently hold valid data and are ready for use for data storage, where each of the plurality of ready-to-use queues is associated with a respective one of the plurality of health grades;
• monitoring fill levels in the plurality of ready-to-use queues;
• based on the monitoring, the controller adjusting at least one health grade threshold in the set of health grade thresholds for the plurality of blocks;
• and
• based on the adjustment of the at least one health grade threshold, thereafter re-grading blocks among the plurality of blocks in the ready-to-use queues with respect to the plurality of health grades and assigning blocks among the plurality of blocks to the plurality of ready-to-use queues in accordance with the at least one health grade threshold that was adjusted, such that distribution of blocks within the plurality of ready-to-use queues is improved.