Data storage system with dynamic erase block grouping mechanism and method of operation thereof

• US 9,665,295 B2
• Filed: 08/26/2016
• Issued: 05/30/2017
• Est. Priority Date: 08/07/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Fitzpatrick, James, Rub, Bernardo, Higgins, James M., Ellis, Robert W., Dancho, Mark
• Primary Examiner(s): Nguyen, Viet Q
• Application Number:
  US15/249,237
• Publication Number:
  US 20160364155A1
• Time in Patent Office: 277 Days
• Field of Search: 36518511, 36518529
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 11/5635 Erasing circuits
• CPC Class Codes: G11C 16/10 Programming or data input circuits
• CPC Class Codes: G11C 16/16 for erasing blocks, e.g. arrays, words, groups
• CPC Class Codes: G11C 16/3495 Circuits or methods to detect or delay wearout of nonvolatile EPROM or EEPROM memory devices, e.g. by counting numbers of erase or reprogram cycles, by using multiple memory areas serially or cyclically

Abstract

Systems, methods and/or devices are used to enable dynamic erase block grouping. In one aspect, the method includes (1) maintaining metadata for each erase block of a plurality of erase blocks in a data storage system, wherein a respective metadata for a respective erase block includes one or more characteristics of the respective erase block, (2) allocating a set of erase blocks, of the plurality of erase blocks, as unassociated erase blocks, (3) selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics, and (4) grouping the two or more unassociated erase blocks with similar characteristics to form a super block.

Claims

1. A method of operation of a data storage system, the method comprising:

maintaining metadata for each erase block of a plurality of erase blocks in the data storage system, wherein a respective metadata for a respective erase block includes one or more characteristics of the respective erase block;

allocating a set of erase blocks, of the plurality of erase blocks, as unassociated erase blocks; and

forming a plurality of super blocks, including, for each super block to be formed;

selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics, wherein said characteristics of the unassociated erase blocks, in accordance with which the two or more unassociated erase blocks are selected, include at least one characteristic selected from the group consisting of age information, bit error rate, wear statistics, and operation parameters;

grouping the two or more selected erase blocks to form the super block;

aggregating metadata from the two or more selected erase blocks; and

storing the aggregated metadata as metadata for the super block.

2. The method of claim 1, wherein the selecting includes enforcing a minimum amount of dwell time for the unassociated erase blocks, wherein dwell time is the amount of time between operations on a respective erase block.

3. The method of claim 1, wherein the metadata is maintained in persistent storage in the data storage system.

4. The method of claim 1, wherein the super block includes two or more unassociated erase blocks from different memory die of the data storage system.

5. The method of claim 1, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes selecting two or more unassociated erase blocks with similar ages.

6. The method of claim 1, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes:

selecting a first unassociated erase block from a first die of the data storage system;

selecting a second unassociated erase block from a second die of the data storage system; and

forgoing selection of a third unassociated erase block from a third die of the data storage system, wherein the third die is relatively worn in comparison to the first die and second die.

7. The method of claim 1, further comprising:

selecting one or more erase blocks, in accordance with the one or more characteristics of the one or more erase blocks, for recycling;

recycling the selected one or more erase blocks; and

allocating the recycled one or more erase blocks as unassociated erase blocks.

8. The method of claim 1, further comprising:

selecting, from the super block, a relatively old erase block to store parity information.

9. A data storage system, comprising:

one or more processors; and

memory storing one or more programs to be executed by the one or more processors, the one or more programs comprising instructions for;

maintaining metadata for each erase block of a plurality of erase blocks in the data storage system, wherein a respective metadata for a respective erase block includes one or more characteristics of the respective erase block;

allocating a set of erase blocks, of the plurality of erase blocks, as unassociated erase blocks; and

forming a plurality of super blocks, including, for each super block to be formed;

selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics, wherein said characteristics of the unassociated erase blocks, in accordance with which the two or more unassociated erase blocks are selected, include at least one characteristic selected from the group consisting of age information, bit error rate, wear statistics, and operation parameters;

grouping the two or more selected erase blocks to form the super block;

aggregating metadata from the two or more selected erase blocks; and

storing the aggregated metadata as metadata for the super block.

10. The data storage system of claim 9, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes enforcing a minimum amount of dwell time for the unassociated erase blocks, wherein dwell time is the amount of time between operations on a respective erase block.

11. The data storage system of claim 9, wherein the metadata is maintained in persistent storage in the data storage system.

12. The data storage system of claim 9, wherein the super block includes two or more unassociated erase blocks from different memory die of the data storage system.

13. The data storage system of claim 9, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes selecting two or more unassociated erase blocks with similar ages.

14. The data storage system of claim 9, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes:

selecting a first unassociated erase block from a first die of the data storage system;

selecting a second unassociated erase block from a second die of the data storage system; and

forgoing selection of a third unassociated erase block from a third die of the data storage system, wherein the third die is relatively worn in comparison to the first die and second die.

15. The data storage system of claim 9, wherein the one or more programs further comprise instructions for:

selecting one or more erase blocks, in accordance with the one or more characteristics of the one or more erase blocks, for recycling;

recycling the selected one or more erase blocks; and

allocating the recycled one or more erase blocks as unassociated erase blocks.

16. The data storage system of claim 9, wherein the one or more programs further comprise instructions for selecting, from the super block, a relatively old erase block to store parity information.

17. A non-transitory computer readable storage medium, storing one or more programs configured for execution by one or more processors of a data storage system, the one or more programs including instructions for:

maintaining metadata for each erase block of a plurality of erase blocks in the data storage system, wherein a respective metadata for a respective erase block includes one or more characteristics of the respective erase block;

allocating a set of erase blocks, of the plurality of erase blocks, as unassociated erase blocks; and

forming a plurality of super blocks, including, for each super block to be formed;

selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics, wherein said characteristics of the unassociated erase blocks, in accordance with which the two or more unassociated erase blocks are selected, include at least one characteristic selected from the group consisting of age information, bit error rate, wear statistics, and operation parameters;

grouping the two or more selected erase blocks to form the super block;

aggregating metadata from the two or more selected erase blocks; and

storing the aggregated metadata as metadata for the super block.

18. The non-transitory computer readable storage medium of claim 17, wherein the selecting includes enforcing a minimum amount of dwell time for the unassociated erase blocks, wherein dwell time is the amount of time between operations on a respective erase block.

19. The non-transitory computer readable storage medium of claim 17, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes selecting two or more unassociated erase blocks with similar ages.

20. The non-transitory computer readable storage medium of claim 17, wherein selecting two or more unassociated erase blocks in accordance with characteristics of the unassociated erase blocks so as to select unassociated erase blocks with similar characteristics includes:

selecting a first unassociated erase block from a first die of the data storage system;

selecting a second unassociated erase block from a second die of the data storage system; and

forgoing selection of a third unassociated erase block from a third die of the data storage system, wherein the third die is relatively worn in comparison to the first die and second die.