Efficient management of page retirement in non-volatile memory utilizing page retirement classes

• US 9,898,215 B2
• Filed: 12/07/2015
• Issued: 02/20/2018
• Est. Priority Date: 12/07/2015
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Camp, Charles J., Fisher, Timothy J., Ioannou, Nikolas, Parnell, Thomas, Pletka, Roman A., Tomic, Sasa
• Primary Examiner(s): Lottich, Joshua P
• Application Number:
  US14/960,661
• Publication Number:
  US 20170160960A1
• Time in Patent Office: 806 Days
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0655 Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

In at least one embodiment, a non-volatile memory array including a plurality of blocks each including a plurality of physical pages is controlled by a controller. The controller implements a plurality of nested page retirement classes each defined by a respective one of a plurality of different nested subsets of page indices of physical pages within the plurality of blocks that are to be considered retired from use. For each block among the plurality of blocks, the controller updating an indication of a page retirement class to which the block belongs in response to detection of a retirement-causing error in a data page stored in a physical page of the block. The controller forms block stripes for storing data from the plurality of blocks based on the page retirement classes of the blocks.

Claims

1. A method in a data storage system including a non-volatile memory array controlled by a controller, wherein the non-volatile memory array includes a plurality of blocks each including a plurality of physical pages, the method comprising:

the controller implementing a plurality of nested page retirement classes each defined by a respective one of a plurality of different nested subsets of page indices of physical pages within the plurality of blocks that are to be considered retired from use;

for each block among the plurality of blocks, the controller updating an indication of a page retirement class to which the block belongs in response to detection of a retirement-causing error in a data page stored in a physical page of the block; and

the controller forming block stripes for storing data from selected ones of the plurality of blocks identified in ready-to-use queues based on the page retirement classes of the blocks.

2. The method of claim 1, wherein the updating includes imprecisely retiring physical pages of the plurality of blocks based on page retirement class.

3. The method of claim 2, wherein:

for at least a particular block among the plurality of blocks, the updating includes associating the particular block with a page retirement class defined by at least a page index of a physical page of the particular block in which no retirement-causing error has been detected, such that the particular page is retired in advance of need.

4. The method of claim 1, and further comprising:

initializing the plurality of nested page retirement classes based on characterization data.

5. The method of claim 1, wherein:

the controller implementing one or more health grades associated with various ones of the plurality of blocks having no physical pages retired from use;

the method further comprises the controller implementing a plurality of sets of ready-to-use queues each including a respective ready-to-use queue for each of the plurality of nested page retirement classes and one or more health grades; and

the forming includes;

forming block stripes from blocks having retired pages by drawing blocks from corresponding ready-to-use queues in the plurality of sets of ready-to-use queues that are associated with page retirement classes; and

forming block stripes from blocks having no retired pages by drawing blocks from corresponding ready-to-use queues in the plurality of sets of ready-to-use queues that are associated with the one or more health grades.

6. The method of claim 1, and further comprising:

the controller determining whether available memory capacity of the memory array is being used efficiently; and

in response to determining that the available memory capacity of the memory array is not being used efficiently, the controller dynamically changing from implementing the nested page retirement classes to implementing pattern-based page retirement classes each defined by a respective one of a plurality of different patterns of page indices of physical pages within the plurality of blocks that are to be considered retired from use.

7. A data storage system, comprising:

a controller configured to be coupled to a non-volatile memory array including a plurality of blocks each including a plurality of physical pages, wherein the controller implements a plurality of nested page retirement classes each defined by a respective one of a plurality of different nested subsets of page indices of physical pages within the plurality of blocks that are to be considered retired from use, and wherein the controller, for each block among the plurality of blocks, updates an indication of a page retirement class to which the block belongs in response to detection of a retirement-causing error in a data page stored in a physical page of the block, and wherein the controller forms block stripes for storing data from selected ones of the plurality of blocks identified in ready-to-use queues based on the page retirement classes of the blocks.

8. The data storage system of claim 7, wherein the controller imprecisely retires physical pages of the plurality of blocks based on page retirement class.

9. The data storage system of claim 8, wherein:

the controller, for at least a particular block among the plurality of blocks, associates the particular block with a page retirement class defined by at least a page index of a physical page of the particular block in which no retirement-causing error has been detected, such that the particular page is retired in advance of need.

10. The data storage system of claim 7, wherein the controller initializes the plurality of nested page retirement classes based on characterization data.

11. The data storage system of claim 7, wherein:

the controller implements one or more health grades associated with various ones of the plurality of blocks having no physical pages retired from use;

the controller implements a plurality of sets of ready-to-use queues each including a respective ready-to-use queue for each of the plurality of nested page retirement classes and one or more health grades;

the controller forms block stripes from blocks having retired pages by drawing blocks from corresponding ready-to-use queues in the plurality of sets of ready-to-use queues that are associated with page retirement classes; and

the controller forms block stripes from blocks having no retired pages by drawing blocks from corresponding ready-to-use queues in the plurality of sets of ready-to-use queues that are associated with the one or more health grades.

12. The data storage system of claim 7, wherein:

the controller determines whether available memory capacity of the memory array is being used efficiently and, responsive to determining that the available memory capacity of the memory array is not being used efficiently, dynamically changing from implementing the nested page retirement classes to implementing pattern-based page retirement classes each defined by a respective one of a plurality of different patterns of page indices of physical pages within the plurality of blocks that are to be considered retired from use.

13. The data storage system of claim 7, and further comprising the non-volatile memory array coupled to the controller.

14. A computer program product, the computer program product comprising:

a storage device having program instructions embodied therewith, the program instructions executable by a controller of a non-volatile memory array including a plurality of blocks each including a plurality of physical pages, to cause the controller to perform;

implementing a plurality of nested page retirement classes each defined by a respective one of a plurality of different nested subsets of page indices of physical pages within the plurality of blocks that are to be considered retired from use;

for each block among the plurality of blocks, updating an indication of a page retirement class to which the block belongs in response to detection of a retirement-causing error in a data page stored in a physical page of the block; and

forming block stripes for storing data from selected ones of the plurality of blocks identified in ready-to-use queues based on the page retirement classes of the blocks.

15. The program product of claim 14, wherein the updating includes imprecisely retiring physical pages of the plurality of blocks based on page retirement class.

16. The program product of claim 15, wherein:

for at least a particular block among the plurality of blocks, the updating includes associating the particular block with a page retirement class defined by at least a page index of a physical page of the particular block in which no retirement-causing error has been detected, such that the particular page is retired in advance of need.

17. The program product of claim 14, wherein the program code further causes the controller to perform:

initializing the plurality of nested page retirement classes based on characterization data.

18. The program product of claim 14, wherein the program code further causes the controller to perform:

implementing one or more health grades associated with various ones of the plurality of blocks having no physical pages retired from use;

implementing a plurality of sets of ready-to-use queues each including a respective ready-to-use queue for each of the plurality of nested page retirement classes and one or more health grades; and

the forming includes;

forming block stripes from blocks having retired pages by drawing blocks from corresponding ready-to-use queues in the plurality of sets of ready-to-use queues that are associated with page retirement classes; and

forming block stripes from blocks having no retired pages by drawing blocks from corresponding ready-to-use queues in the plurality of sets of ready-to-use queues that are associated with the one or more health grades.

19. The program product of claim 14, wherein the program code further causes the controller to perform:

determining whether available memory capacity of the memory array is being used efficiently; and

in response to determining that the available memory capacity of the memory array is not being used efficiently, dynamically changing from implementing the nested page retirement classes to implementing pattern-based page retirement classes each defined by a respective one of a plurality of different patterns of page indices of physical pages within the plurality of blocks that are to be considered retired from use.