Device and method for managing die groups

• US 9,442,662 B2
• Filed: 12/20/2013
• Issued: 09/13/2016
• Est. Priority Date: 10/18/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Dancho, Mark, Fitzpatrick, James, Li, Li
• Primary Examiner(s): DUDEK JR, EDWARD J
• Application Number:
  US14/137,511
• Publication Number:
  US 20150113203A1
• Time in Patent Office: 998 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• 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

The embodiments described herein methods and devices that enhance the endurance of a non-volatile memory (e.g., flash memory). The method includes obtaining, for each of the plurality of die, an endurance metric. The method also includes sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics, where each die group includes one or more die and each die group is associated with a range of endurance metrics. In response to a write command specifying a set of write data, the method further includes writing the write data to the non-volatile memory by writing in parallel subsets of the write data to the one or more die assigned to a single die group of the plurality of die groups.

Claims

1. A method of managing a storage system that comprises a storage controller and non-volatile memory, the non-volatile memory comprising a plurality of die and each die comprising a plurality of subunits, the method comprising:

at the storage controller coupled with the non-volatile memory;

for each of the plurality of die, obtaining an endurance metric;

sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics, wherein each die group includes one or more die and each die group is associated with a corresponding range of endurance metrics, and wherein a plurality of the die groups each includes two or more die;

storing a die group mapping in the storage controller that indicates which die are assigned to each die group of the plurality of die groups, wherein the storage controller includes a logical address to physical address mapping distinct from the die group mapping; and

in response to a write command specifying a set of write data, writing the set of write data to the non-volatile memory by writing in parallel distinct respective subsets of the set of write data to distinct respective die assigned to a single die group of the plurality of die groups.

2. The method of claim 1, wherein obtaining the endurance metric for each of the plurality of die includes performing a calibration routine on a representative subunit in each of the plurality of die to generate the endurance metric for each of the plurality of die.

3. The method of claim 1, wherein the plurality of die groups includes at least four die groups, and writing the write data includes mapping, in the logical address to physical address mapping, logical addresses of the write data to physical addresses in the non-volatile memory in accordance with the die group mapping in the storage controller that indicates which die are assigned to each die group of the plurality of die groups.

4. The method of claim 1, further comprising:

selecting a die group based on an operation to be performed and the endurance metrics of die assigned to the die group.

5. The method of claim 1, further comprising:

after a predefined condition occurs;

obtaining, for each of the plurality of die, an updated endurance metric; and

re-sorting the plurality of die into a plurality of updated die groups based on their corresponding updated endurance metrics, wherein each updated die group includes one or more die and each updated die group is associated with a corresponding range of endurance metrics.

6. The method of claim 5, further comprising:

after re-sorting the plurality of die into a plurality of updated die groups, updating the die group mapping, the die group mapping including a table of logical addresses of die comprising each die group.

7. The method of claim 1, wherein a plurality of channels communicatively couple the storage controller to the non-volatile memory, wherein each channel is communicatively coupled with a respective subset of the plurality of die, the method further comprising:

for each channel, ranking the die in the channel in accordance with the endurance metrics of the respective die in the channel; and

wherein sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics includes assigning, based on the ranking of the die in each of the channels, to each die group of a plurality of die groups, one or more die from each channel, wherein the die assigned to a respective die group have a rank, or range of ranks, corresponding to the respective die group, and each die group has a distinct corresponding rank or range of ranks.

8. The method of claim 7, further comprising:

after a predefined condition occurs;

obtaining, for each of the plurality of die, an updated endurance metric;

for each channel, re-ranking the die in the channel in accordance with the updated endurance metrics of the respective die in the channel; and

based on the re-ranking of the die in each of the channels, assigning to each die group one or more die from each channel.

9. The method of claim 8, further comprising:

after assigning one or more die from each channel to each die group based on the re-ranking of the die in each of the channels, updating the die group mapping, the die group mapping including a table of logical addresses of die comprising each die group.

10. A storage controller, comprising:

one or more processors;

a host interface configured to couple the storage controller to a host;

a storage medium interface configured to couple the storage controller to non-volatile memory comprising a plurality of die, each die comprising a plurality of subunits; and

a storage controller memory storing instructions, which, when executed by the one or more processors, cause the storage controller to perform operations comprising;

for each of the plurality of die, obtaining an endurance metric;

sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics, wherein each die group includes one or more die and each die group is associated with a corresponding range of endurance metrics, and wherein a plurality of the die groups each includes two or more die;

storing a die group mapping in the storage controller that indicates which die are assigned to each die group of the plurality of die groups, wherein the storage controller includes a logical address to physical address mapping distinct from the die group mapping; and

in response to a write command specifying a set of write data, writing the set of write data to the non-volatile memory by writing in parallel distinct respective subsets of the set of write data to distinct respective die assigned to a single die group of the plurality of die groups.

11. The storage controller of claim 10, wherein obtaining the endurance metric for each of the plurality of die includes performing a calibration routine on a representative subunit in each of the plurality of die to generate the endurance metric for each of the plurality of die.

12. The storage controller of claim 10, wherein the plurality of die groups includes at least four die groups, and writing the write data includes mapping, in the logical address to physical address mapping, logical addresses of the write data to physical addresses in the non-volatile memory in accordance with the die group mapping in the storage controller that indicates which die are assigned to each die group of the plurality of die groups.

13. The storage controller of claim 10, wherein the instructions cause the storage controller to perform operations further comprising:

selecting a die group based on an operation to be performed and the endurance metrics of die assigned to the die group.

14. The storage controller of claim 10, wherein the instructions cause the storage controller to perform operations further comprising:

after a predefined condition occurs;

obtaining, for each of the plurality of die, an updated endurance metric; and

re-sorting the plurality of die into a plurality of updated die groups based on their corresponding updated endurance metrics, wherein each updated die group includes one or more die and each updated die group is associated with a corresponding range of endurance metrics.

15. The storage controller of claim 14, wherein the instructions cause the storage controller to perform operations further comprising:

after re-sorting the plurality of die into a plurality of updated die groups, updating the die group mapping, the die group mapping including a table of logical addresses of die comprising each die group.

16. The storage controller of claim 10, wherein:

a plurality of channels communicatively couple the storage controller to the non-volatile memory, wherein each channel is communicatively coupled with a respective subset of the plurality of die; and

the instructions cause the storage controller to perform operations further comprising;

for each channel, ranking the die in the channel in accordance with the endurance metrics of the respective die in the channel; and

wherein sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics includes assigning, based on the ranking of the die in each of the channels, to each die group of a plurality of die groups, one or more die from each channel, wherein the die assigned to a respective die group have a rank, or range of ranks, corresponding to the respective die group, and each die group has a distinct corresponding rank or range of ranks.

17. A non-transitory computer readable storage medium, storing one or more programs for execution by one or more processors of a storage controller communicatively coupled with non-volatile memory comprising a plurality of die and each die comprising a plurality of subunits, the one or more programs including instructions that when executed by the one or more processors cause the storage controller to:

for each of the plurality of die, obtain an endurance metric;

sort the plurality of die into a plurality of die groups based on their corresponding endurance metrics, wherein each die group includes one or more die and each die group is associated with a corresponding range of endurance metrics, and wherein a plurality of the die groups each includes two or more die;

storing a die group mapping in the storage controller that indicates which die are assigned to each die group of the plurality of die groups, wherein the storage controller includes a logical address to physical address mapping distinct from the die group mapping; and

in response to a write command specifying a set of write data, write the set of write data to the non-volatile memory by writing in parallel distinct respective subsets of the set of write data to distinct respective die assigned to a single die group of the plurality of die groups.

18. The non-transitory computer readable storage medium of claim 17, wherein obtaining the endurance metric for each of the plurality of die includes performing a calibration routine on a representative subunit in each of the plurality of die to generate the endurance metric for each of the plurality of die.

19. The non-transitory computer readable storage medium of claim 17, wherein the plurality of die groups includes at least four die groups, and writing the write data includes mapping, in the logical address to physical address mapping, logical addresses of the write data to physical addresses in the non-volatile memory in accordance with the die group mapping in the storage controller that indicates which die are assigned to each die group of the plurality of die groups.

20. The non-transitory computer readable storage medium of claim 17, wherein the one or more programs further include instructions that when executed by the one or more processors cause the storage controller to:

select a die group based on an operation to be performed and the endurance metrics of die assigned to the die group.

21. The non-transitory computer readable storage medium of claim 17, wherein the one or more programs further include instructions that when executed by the one or more processors cause the storage controller to:

after a predefined condition occurs;

obtain, for each of the plurality of die, an updated endurance metric; and

re-sort the plurality of die into a plurality of updated die groups based on their corresponding updated endurance metrics, wherein each updated die group includes one or more die and each updated die group is associated with a corresponding range of endurance metrics.

22. The non-transitory computer readable storage medium of claim 21, wherein the one or more programs further include instructions that when executed by the one or more processors cause the storage controller to:

after re-sorting the plurality of die into a plurality of updated die groups, update the die group mapping, the die group mapping including a table of logical addresses of die comprising each die group.

23. The non-transitory computer readable storage medium of claim 17, wherein:

a plurality of channels communicatively couple the storage controller to the non-volatile memory, wherein each channel is communicatively coupled with a respective subset of the plurality of die; and

the one or more programs further include instructions that when executed by the one or more processors cause the storage controller to;

for each channel, rank the die in the channel in accordance with the endurance metrics of the respective die in the channel; and

wherein sorting the plurality of die into a plurality of die groups based on their corresponding endurance metrics includes assigning, based on the ranking of the die in each of the channels, to each die group of a plurality of die groups, one or more die from each channel, wherein the die assigned to a respective die group have a rank, or range of ranks, corresponding to the respective die group, and each die group has a distinct corresponding rank or range of ranks.