Endurance enhancement scheme using memory re-evaluation

• US 10,339,048 B2
• Filed: 12/23/2014
• Issued: 07/02/2019
• Est. Priority Date: 12/23/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Camp, Charles J., Fisher, Timothy J., Fry, Aaron D., Ioannou, Nikolas, Koltsidas, Ioannis, Pletka, Roman, Tomic, Sasa
• Primary Examiner(s): Thammavong, Prasith
• Assistant Examiner(s): Olson, Alex G
• Application Number:
  US14/581,976
• Publication Number:
  US 20160179412A1
• Time in Patent Office: 1,652 Days
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0261 using reference counting
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices

Abstract

An apparatus, according to one embodiment, includes non-volatile memory configured to store data, and a controller and logic integrated with and/or executable by the controller, the logic being configured to: determine, by the controller, that at least one block of the non-volatile memory and/or portion of a block of the non-volatile memory meets a retirement condition, re-evaluate, by the controller, the at least one block and/or the portion of a block to determine whether to retire the at least one block and/or the portion of a block, indicate, by the controller, that the at least one block and/or the portion of a block remains usable when a result of the re-evaluation is not to retire the block, and indicate, by the controller, that the at least one block and/or the portion of a block is retired when the result of the re-evaluation is to retire the block.

Claims

1. An apparatus, comprising:

non-volatile memory configured to store data; and

a controller and logic integrated with and/or executable by the controller, the logic being configured to;

determine, by the controller, that at least one block of the non-volatile memory and/or portion of a block of the non-volatile memory meets a retirement condition;

re-evaluate, by the controller, the at least one block and/or the portion of a block to determine whether to retire the at least one block and/or the portion of a block;

indicate, by the controller, that the at least one block and/or the portion of a block remains usable when a result of the re-evaluation is not to retire the block; and

indicate, by the controller, that the at least one block and/or the portion of a block is retired when the result of the re-evaluation is to retire the block,

wherein the re-evaluating includes;

assigning the at least one block and/or the portion of a block into a delay queue for at least a dwell time and/or a read delay,

performing one or more erase operations on the at least one block and/or the portion of a block,

writing data to the at least one block and/or the portion of a block,

performing a calibration of the at least one block and/or the portion of a block, and

performing a read sweep on the at least one block and/or the portion of a block,

wherein performing the calibration includes determining an optimal threshold voltage shift value for each of the at least one block and/or the portion of a block.

2. The apparatus as recited in claim 1, wherein the re-evaluating includes assigning the at least one block and/or the portion of a block to a delay queue for at least a dwell time.

3. The apparatus as recited in claim 1, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that any of the one or more erase operations fail.

4. The apparatus as recited in claim 1, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that one or more write errors have occurred.

5. The apparatus as recited in claim 1, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that a number of calibration errors exceeds a retirement error count limit.

6. The apparatus as recited in claim 1, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that a number of read errors exceeds a retirement error count limit.

7. The apparatus as recited in claim 1, wherein the non-volatile memory includes NAND Flash memory, wherein the re-evaluating is performed in response to determining that the at least one block of the non-volatile memory and/or portion of the block of the non-volatile memory meets the retirement condition.

8. A computer-implemented method, comprising:

determining, by a computer, that at least one block of a non-volatile memory and/or portion of a block of the non-volatile memory meets a retirement condition;

re-evaluating, by the computer, that the at least one block and/or the portion of a block to determine whether to retire the at least one block and/or the portion of a block;

indicating, by the computer, that the at least one block and/or the portion of a block remains usable when a result of the re-evaluation is not to retire the block; and

indicating, by the computer, that the at least one block and/or the portion of a block is retired when the result of the re-evaluation is to retire the block,

wherein the re-evaluating includes;

assigning the at least one block and/or the portion of a block into a delay queue for at least a dwell time and/or a read delay;

performing one or more erase operations on the at least one block and/or the portion of a block;

writing data to the at least one block and/or the portion of a block;

performing a calibration of the at least one block and/or the portion of a block; and

performing a read sweep on the at least one block and/or the portion of a block,

wherein performing the calibration includes determining an optimal threshold voltage shift value for each of the at least one block and/or the portion of a block.

9. The method as recited in claim 8, wherein the re-evaluating includes assigning the at least one block and/or the portion of a block to a delay queue for at least a dwell time.

10. The method as recited in claim 8, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that any of the one or more erase operations fail.

11. The method as recited in claim 8, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that one or more write errors have occurred.

12. The method as recited in claim 8, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that a number of calibration errors exceeds a retirement error count limit.

13. The method as recited in claim 8, wherein the result of the re-evaluation is to retire the at least one block and/or the portion of a block in response to determining that a number of read errors exceeds a retirement error count limit.

14. The method as recited in claim 8, wherein the non-volatile memory includes NAND Flash memory, wherein the re-evaluating is performed in response to determining that the at least one block of the non-volatile memory and/or portion of the block of the non-volatile memory meets the retirement condition.

15. A computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a controller to cause the controller to:

determine, by the controller, that at least one block of a non-volatile memory and/or portion of a block of the non-volatile memory meets a retirement condition;

re-evaluate, by the controller, the at least one block and/or the portion of a block to determine whether to retire the at least one block and/or the portion of a block;

indicate, by the controller, that the at least one block and/or the portion of a block remains usable when a result of the re-evaluation is not to retire the block; and

indicate, by the controller, that the at least one block and/or the portion of a block is retired when the result of the re-evaluation is to retire the block,

wherein the re-evaluating includes at least one of;

assigning the at least one block and/or the portion of a block into a delay queue for at least a dwell time and/or a read delay;

performing one or more erase operations on the at least one block and/or the portion of a block;

writing data to the at least one block and/or the portion of a block;

performing a calibration of the at least one block and/or the portion of a block; and

performing a read sweep on the at least one block and/or the portion of a block.

16. The computer program product as recited in claim 15, wherein the re-evaluating includes:

assigning the at least one block and/or the portion of a block into a delay queue for at least a dwell time and/or a read delay;

performing one or more erase operations on the at least one block and/or the portion of a block;

writing data to the at least one block and/or the portion of a block;

performing a calibration of the at least one block and/or the portion of a block; and

performing a read sweep on the at least one block and/or the portion of a block,

wherein performing the calibration includes determining an optimal threshold voltage shift value for each of the at least one block and/or the portion of a block.

17. The computer program product as recited in claim 15, wherein the non-volatile memory includes NAND Flash memory, wherein the re-evaluating is performed in response to determining that the at least one block of the non-volatile memory and/or portion of the block of the non-volatile memory meets the retirement condition.