SYSTEM AND METHOD OF MANAGING DATA IN A NON-VOLATILE MEMORY HAVING A STAGING SUB-DRIVE

• US 20180190329A1
• Filed: 12/29/2016
• Published: 07/05/2018
• Est. Priority Date: 12/29/2016
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Granted Patent: US 10,032,488 B1
• Time in Patent Office: Days
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/1041 Resource optimization
• CPC Class Codes: G06F 2212/1044 Space efficiency improvement
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G11C 7/04 with means for avoiding disturbances due to temperature effects

Abstract

A system and method is disclosed for managing data in a non-volatile memory. The system may include a non-volatile memory having multiple non-volatile memory sub-drives, including a staging sub-drive to receive all data from a host and a plurality of other sub-drives each associated with a respective data temperature range. A controller of the memory system is configured to route all incoming host data only to the staging sub-drive and during garbage collection each individual piece of valid data from a selected source block in a selected source sub-drive is routed to a respective one of the sub-drives. The method may include only routing host data to the staging sub-drive and only relocating valid data to sub-drives other than the staging sub-drive based on a determined temperature of valid data and a unique temperature range associated with sub-drives other than the staging sub-drive in the non-volatile memory system.

Claims

1. A method for managing data in a memory system having a controller in communication with a plurality of non-volatile memory sub-drives, the method comprising the controller:

receiving host data writes at the memory system;

storing all data associated with the received host data writes only at a staging sub-drive of the plurality of sub-drives;

only moving data from the staging sub-drive to another sub-drive as part of a garbage collection operation to free additional space in the staging sub-drive.

2. The method of claim 1, further comprising:

determining, based on a garbage collection trigger, whether a garbage collection operation is necessary for the staging sub-drive; and

executing the garbage collection operation when the garbage collection threshold is determined to be necessary.

3. The method of claim 1, wherein the garbage collection trigger comprises a number of free blocks in the plurality of sub-drives falling below a predetermined threshold.

4. The method of claim 3, wherein the free blocks comprise free superblocks.

5. The method of claim 1, further comprising only maintaining an open write superblock for receiving host data on the staging sub-drive and only maintaining an open relocation superblock on each of the plurality of sub-drives in the memory system other than the staging sub-drive.

6. The method of claim 2, wherein executing the garbage collection operation comprises selecting a superblock in the staging sub-drive as a source block for relocation and relocating each valid data piece in the selected block to a sub-drive other than the staging sub-drive, wherein each valid data piece is relocated directly from the staging sub-drive to a respective one of the other sub-drives based on a determined temperature of the data in each valid data piece.

7. The method of claim 6, further comprising determining a temperature of a valid data piece based on an average temperature of a logical block address (LBA) block that includes a logical block address of the valid data piece, wherein the average temperature of the LBA block comprises an average number of host actions on logical block addresses included in the LBA block.

8. The method of claim 7 wherein the host actions comprise host writes.

9. A method for managing data, the method comprising:

in a memory system having a controller and plurality of non-volatile memory sub-drives including a staging sub-drive configured to receive all initial data writes from a host and plurality of additional sub-drives each associated with data of a different predetermined temperature range, the controller;

selecting one of the plurality of non-volatile memory sub-drives for a garbage collection operation;

selecting a source superblock for the garbage collection operation in the selected one of the plurality of sub-drives, the selected source superblock having valid data pieces each associated with a respective logical address;

for each valid data piece in the selected source superblock, determining a temperature of the logical address associated with the valid data piece; and

moving the valid data piece to the non-volatile memory sub-drive containing data associated with logical addresses having the determined temperature.

10. The method of claim 9, wherein the selecting one of the plurality of non-volatile memory sub-drives comprises selecting a sub-drive that has a current overprovisioning greater than a target overprovisioning for the sub-drive, wherein overprovisioning comprises a ratio of physical space in the sub-drive to an amount of valid data in the sub-drive.

11. The method of claim 9, wherein determining the temperature comprises determining an amount of host activity previously directed to a logical address associated with the valid data piece.

12. The method of claim 9, wherein determining the temperature further comprises determining the amount of host activity previously directed to the logical address over a predetermined time.

13. The method of claim 12, wherein the memory system comprises a logical address space divided into a plurality of predetermined contiguous logical address blocks, and wherein determining the temperature comprises determining an average amount of host activity previously directed to a contiguous logical block address block containing a logical address of the valid data piece and associating the determined average amount of host activity to the logical address.

14. The method of claim 9, wherein when the selected sub-drive comprises the staging sub-drive, only moving each valid data piece to a sub-drive other than the staging sub-drive.

15. The method of claim 9, wherein when the selected sub-drive comprises a sub-drive other than the staging sub-drive, only moving each valid data piece to a sub-drive other than the staging sub-drive.

16. A non-volatile memory system comprising:

a non-volatile memory having a plurality of sub-drives; and

a controller in communication with the plurality of sub-drives, the controller configured to;

only route data received from a host to a staging sub-drive;

select from the plurality of sub-drives a sub-drive having more than a target amount of overprovisioning for the sub-drive, wherein the target amount of overprovisioning comprises a ratio of physical storage capacity to valid data in the sub-drive;

select a source superblock from the selected sub-drive for the garbage collection operation;

execute a garbage collection operation on the selected source block, wherein to execute the garbage collection operation, the controller is configured to only relocate valid data pieces of the selected source superblock to sub-drives other than the staging sub-drive based on a data temperature range associated with the sub-drives other than the staging sub-drive and a data temperature determined for each valid data piece.

17. The non-volatile memory system of claim 16, further comprising:

a plurality of logical block address (LBA) blocks, each LBA block defining a unique contiguous range of LBAs;

a plurality of host activity counters, each host activity counter associated with a respective one of the plurality of LBA blocks; and

wherein for each of the plurality of host activity counters the controller is further configured to track a host activity count for all host activity at LBAs associated with a respective LBA block.

18. The non-volatile memory system of claim 17, wherein to determine a data temperature of a valid data piece, the controller is configured to:

determine an average host activity count for each LBA block; and

assign the valid data piece, as the data temperature, the average host activity count of an LBA block containing the LBA associated with the valid data piece.

19. The non-volatile memory system of claim 17, wherein the controller is configured to track the host activity count for all host activity over a predetermined time period at LBAs associated with the respective LBA block.

20. The non-volatile memory system of claim 17, wherein the non-volatile memory comprises a substrate formed with a three-dimensional memory structure.

21. A non-volatile memory system comprising:

a non-volatile memory comprising;

a staging sub-drive configured to receive all host data from a host; and

a plurality of temperature range sub-drives other than the staging sub-drive, each of the plurality of temperature range sub-drives associated with a respective different data temperature range; and

means for selecting a source superblock for a garbage collection operation from one of the staging sub-drive or plurality of temperature range sub-drives based on a target overprovisioning for each sub-drive and for only relocating valid data from the selected source superblock to sub-drives other than the staging sub-drive based on a data temperature range associated with the sub-drives other than the staging sub-drive and a data temperature determined for each valid data piece in the selected source superblock.