Run-time testing of memory locations in a non-volatile memory

A memory system, comprising:

• a non-volatile memory comprising a plurality of dies, wherein each of the dies comprises a plurality of blocks;
• a controller configured to:
• select one of the dies to perform a test, wherein the selected die comprises a first plurality of unused blocks and a second plurality of blocks programmed with user data;
• choose at least one of the unused blocks in the selected die;
• and
• perform the test on the chosen blocks.

A method of identifying a cause of run-time errors in a first block of a non-volatile memory, the method comprising:

• performing garbage collection on the first block to free the first block for a run-time test;
• selecting a second block for the run-time test, wherein the second block is on the same die as the first block;
• performing run-time tests on the first and second blocks;
• and
• comparing results of testing the first block to results of testing the second block to determine whether the errors of the first block are die-wide or block-specific.