Methods and systems for monitoring write operations of non-volatile memory

• US 9,146,821 B2
• Filed: 05/01/2014
• Issued: 09/29/2015
• Est. Priority Date: 07/26/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Byom, Matthew J., Wakrat, Nir J.
• Primary Examiner(s): GUYTON, PHILIP A
• Application Number:
  US14/267,277
• Publication Number:
  US 20140245084A1
• Time in Patent Office: 516 Days
• Field of Search: 714/42, 714/718, 714/763, 714/773
• US Class Current: 1/1
• CPC Class Codes: G06F 11/073 in a memory management context, e.g. virtual memory or cache management memory management G06F12/00; testing of static memory units G11C29/00
• CPC Class Codes: G06F 11/0757 by exceeding a time limit, i.e. time-out, e.g. watchdogs
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7204 Capacity control, e.g. partitioning, end-of-life degradation
• CPC Class Codes: G06F 2212/7211 Wear leveling

Abstract

Systems and methods are disclosed for monitoring the time it takes to perform a write operation, and based on the time it takes, a determination is made whether to retire a block that is a recipient of the write operation. The time duration of the write operation for a page or a combination of pages may indicate whether any block or blocks containing the page or combination of pages is experiencing a physical failure. That is, if the time duration of the write operation for a particular page exceeds time threshold, this may indicate that this page requires a larger number of program cycles than other pages. The longer programming cycle can be an indication of cell leakage or a failing block.

Claims

1. A system having non-volatile memory comprising:

a non-volatile memory (NVM) including a plurality of blocks;

a controller in operative communication with the NVM, the controller operative to;

write data into at least one portion of the block;

determine a time period, Tprogram, it takes for data to be programmed into each of the at least one portion;

determine if the Tprogram time period falls within a lower bound and an upper bound of a Tprogram threshold; and

in response to determining that the Tprogram time period falls within the lower and upper bounds of the Tprogram threshold, determine whether to retire the block containing the at least one page based on at least one characteristic associated with the at least one portion.

2. The system of claim 1, wherein the Tprogram threshold is set to identify a portion that is potentially experiencing a physical failure.

3. The system of claim 1, the at least one portion may be added to a data structure designed to keep track of pages exhibiting longer Tprogram time periods.

4. The system of claim 1, wherein if the Tprogram time period exceeds the upper bound, the block containing the at least one page having the Tprogram time that exceeds the upper bound is retired.

5. The system of claim 1, wherein the controller is operative to receive feedback data from the NVM to determine the Tprogram time period.

6. A system having non-volatile memory comprising:

a non-volatile memory (NVM) including a plurality of blocks;

a controller in operative communication with the NVM, the controller operative to;

obtain timing data for at least one portion in at least one block, the timing data associated with a time duration to perform a write operation;

apply criteria to the timing data, wherein the criteria comprises a lower time threshold and an upper time threshold; and

determine whether to retire the at least one block if the criteria falls within the lower and upper time thresholds.

7. The system of claim 6, wherein the timing data comprises a time duration to buffer data and a time duration to program data.

8. The system of claim 7, wherein the controller is operative to determine if the time duration to program data exceeds the upper time threshold.

9. The system of claim 6, wherein the controller is operative to obtain the timing data for each programmed portion in a block.

10. The system of claim 6, wherein the controller is operative to obtain timing data for at least one portion in each block of a superblock.