DYNAMIC MANAGEMENT OF GARBAGE COLLECTION AND OVERPROVISIONING FOR HOST STREAM STORAGE

• US 20180357159A1
• Filed: 10/13/2017
• Published: 12/13/2018
• Est. Priority Date: 06/12/2017
• Status: Active Grant

• Current Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Original Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Inventors: Parker, Liam Michael, Gorobets, Sergey Anatolievich, Acosta, Marc
• Granted Patent: US 10,452,536 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 2212/702 Conservative garbage collection
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/061 Improving I/O performance
• 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 3/0653 Monitoring storage devices or systems
• 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

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. A controller of the memory system is configured receive data streams from multiple different host systems and keep data for the separate streams in separate sub-drives. The method may include dynamically changing overprovisioning of the sub-drives in response to changes in relative workload measurements of data writes coming from the different host systems.

Claims

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

receiving host data writes of a plurality of data streams from a plurality of host sources at the memory system;

for each of the plurality of data streams, storing all received host writes only in a respective one sub-drive of the plurality of sub-drives;

measuring a host write workload of each of the plurality of sub-drives; and

altering an amount of overprovisioning of one of the plurality of sub-drives in response to a change in the measured host write workload of another of the plurality of sub-drives.

2. The method of claim 1, wherein altering the amount of overprovisioning of the one of the plurality of sub-drives comprises:

selecting a source superblock from the one of the plurality of sub-drives;

relocating valid data from the selected source superblock only into a relocation superblock in the one of the plurality of sub-drives; and

assigning the source superblock to a shared free block pool for the non-volatile memory system after relocating the valid data.

3. The method of claim 1, wherein measuring the host write workload comprises:

detecting a garbage collection trigger; and

in response to detecting the garbage collection trigger determining a percentage of host writes sent to each of the plurality of sub-drives for a predetermined window of time.

4. The method of claim 3, wherein altering the amount of overprovisioning of one of the plurality of sub-drives in response to a change in the measured host write workload of another of the plurality of sub-drives comprises:

for each respective sub-drive, determining a target overprovisioning amount based on the determined percentage of host writes sent to the respective sub-drive, and based on a percentage of a total valid logical space of the memory system in the respective sub-drive; and

performing a garbage collection operation in a selected sub-drive of the plurality of sub-drives, wherein the selected sub-drive comprises a sub-drive having a greatest amount of actual overprovisioning above the target overprovisioning amount determined for that sub-drive.

5. The method of claim 4, wherein performing the garbage collection operation comprises:

relocating valid data from a selected source superblock in the selected sub-drive only into a relocation superblock in the selected sub-drive; and

assigning the source superblock to a shared free block pool for the non-volatile memory system after relocating the valid data.

6. The method of claim 5, further comprising selecting a superblock having a least amount of valid data in the selected sub-drive as the selected source superblock.

7. The method of claim 3, wherein altering the amount of overprovisioning of one of the plurality of sub-drives in response to a change in the measured host write workload of another of the plurality of sub-drives comprises:

for each respective sub-drive of the plurality of sub-drives determining a target overprovisioning amount based on the determined percentage of host writes sent to the respective sub-drive, and based on a percentage of a total valid logical space of the memory system in the respective sub-drive; and

performing a garbage collection operation in a selected sub-drive of the plurality of sub-drives, wherein the selected sub-drive comprises a sub-drive having a greatest amount of actual overprovisioning above a greater of the target overprovisioning amount determined for that sub-drive or any predetermined minimum overprovisioning associated with the sub-drive.

8. The method of claim 1, further comprising the controller storing a recent current workload calculation for the one for the plurality of sub-drives when the one of the plurality of sub-drives becomes idle.

9. The method of claim 8, further comprises the controller:

retrieving the recent current workload calculation for the one for the plurality of sub-drives, when the one of the plurality of sub-drives becomes active after being idle; and

applying the recent current workload calculation as a current workload calculation to a new overprovisioning determination for all of the plurality of sub-drives.

10. A non-volatile memory system for managing data from a plurality of hosts, the system comprising:

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

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

receive host data writes of a plurality of data streams from the plurality of hosts;

maintain data from each of the plurality of data streams in a different respective separate sub-drive;

measure a host write workload of each of the plurality of sub-drives;

determine a respective target overprovisioning level for each of the plurality of sub-drives based on a relative host write workload of each of the plurality of sub-drives; and

adjust an overprovisioning of one of the plurality of sub-drives in accordance with the respective target overprovisioning level determined for the one of the plurality of sub-drives.

11. The non-volatile memory system of claim 10, wherein the non-volatile memory comprises a substrate formed with a three-dimensional memory structure.

12. The non-volatile memory system of claim 10, wherein to adjust the overprovisioning, the controller is configured to perform a garbage collection operation on the one of the plurality of sub-drives.

13. The non-volatile memory system of claim 12, wherein to perform a garbage collection operation to adjust the overprovisioning, the controller is configured to:

select a source superblock from the one of the plurality of sub-drives;

relocate valid data from the selected source superblock only into a relocation superblock in the one of the plurality of sub-drives; and

after relocating the valid data from the selected source superblock, assign the source block to a shared free block pool for the non-volatile memory system.

14. The non-volatile memory system of claim 10, wherein to measure the host write workload the controller is further configured to:

detect a garbage collection trigger; and

in response to detecting the garbage collection trigger, determine a current workload of an amount of host writes for a predetermined window of time for each of the plurality of sub-drives.

15. The non-volatile memory system of claim 10, wherein the controller is configured to, in response to one of the plurality of sub-drives becoming idle, store a recent current workload calculation for the one for the plurality of sub-drives.

16. The non-volatile memory system of claim 15, wherein the controller is configured to:

retrieve the recent current workload calculation stored for the one for the plurality of sub-drives when the one of the plurality of sub-drives becomes active after being idle; and

apply the recent current workload calculation as a current workload calculation to a new overprovisioning determination for all of the plurality of sub-drives.

17. The non-volatile memory system of claim 10, wherein the controller is configured to determine the respective target overprovisioning level for each of the plurality of sub-drives based on a percentage of host writes sent to each respective sub-drive, and based on a percentage of a total valid logical space of the non-volatile memory system assigned to the respective sub-drive;

and

wherein to adjust the overprovisioning of one of the plurality of sub-drives, the controller is configured to;

select a sub-drive having a greatest amount of actual overprovisioning above the respective target overprovisioning level determined for that sub-drive; and

perform a garbage collection operation on the selected sub-drive.

18. The non-volatile memory system of claim 17, wherein the controller is configured to determine the respective target overprovisioning level for each of the plurality of sub-drives according to a relation:

19. A non-volatile memory system for managing data from a plurality of hosts, the system comprising:

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

means for receiving host data writes of a plurality of different data streams from a plurality of host sources at the memory system and for storing all received host writes for each particular different data stream only in a respective one of the plurality of sub-drives;

means for measuring a host write workload of each of the plurality of sub-drives; and

means for altering an amount of overprovisioning of one of the plurality of sub-drives in response to a change in the measured host write workload of another of the plurality of sub-drives.

20. The non-volatile memory system of claim 19, wherein the means for altering the amount of overprovisioning comprises:

means for determining a target overprovisioning amount in a particular sub-drive based on a determined percentage of host writes sent to the particular sub-drive and on a percentage of a total valid logical space of the memory system in the particular sub-drive; and

means for performing a garbage collection operation in a selected sub-drive of the plurality of sub-drives, wherein the selected sub-drive comprises a sub-drive having a greatest amount of actual overprovisioning above the target overprovisioning amount determined for that sub-drive.