Storage control system with data management mechanism and method of operation thereof

• US 10,546,648 B2
• Filed: 04/12/2013
• Issued: 01/28/2020
• Est. Priority Date: 04/12/2013
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Higgins, James M., Kresse, James M., Jones, Ryan, Dancho, Mark
• Primary Examiner(s): Sain, Gautam
• Application Number:
  US13/862,314
• Publication Number:
  US 20140310494A1
• Time in Patent Office: 2,482 Days
• Field of Search: 711103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

A storage control system, and a method of operation thereof, including: a recycle write queue for providing a recycle write; a host write queue for providing a host write; and a scheduler, coupled to the recycle write queue and the host write queue, for scheduling the recycle write and the host write for writing to a memory device.

Claims

1. A method of operation of a storage control system for a memory device comprising:

receiving at least one recycle write from a recycle write queue;

receiving at least one host write from a host write queue;

identifying a target recycle ratio in accordance with a current size of a spare pool of erased non-volatile memory blocks available to be written to, wherein the target recycle ratio is a targeted ratio of recycling page writes to host page writes;

placing the at least one recycle write and the at least one host write in a write operation queue in accordance with the target recycle ratio;

dispatching the at least one recycle write and the at least one host write from the write operation queue for writing data to the memory device;

during operation of the storage control system, updating the target recycle ratio in accordance with a change in the current size of the spare pool; and

after updating the target recycle ratio;

placing one or more recycle writes and one or more host writes in the write operation queue in accordance with the updated target recycle ratio; and

dispatching the one or more recycle writes and the one or more host writes from the write operation queue for writing data to the memory device.

2. The method as claimed in claim 1 wherein updating the target recycle ratio in accordance with a change in the current size of the spare pool comprises increasing the target recycle ratio in accordance with a decrease in size of the spare pool or decreasing the target recycle ratio in accordance with an increase in size of the spare pool.

3. The method as claimed in claim 1, wherein identifying a target recycle ratio includes the storage control system dynamically determining a first steady-state recycle ratio in a first steady state of the storage control system with respect to number of recycle write operations that are performed per host page write operation;

and

wherein updating the target recycle ratio in accordance with a change in the current size of the spare pool includes detecting a change in the current size of the spare pool that satisfies predefined criteria, and the storage control system, in response to detecting the change in the current size of the spare pool that satisfies the predefined criteria, updating the target recycle ratio to a second steady-state recycle ratio in a second steady state of the storage control system with respect to number of recycle write operations that are performed per host page write operation, wherein the second steady-state recycle ratio is different from the first steady-state recycle ratio.

4. The method as claimed in claim 1 wherein identifying a target recycle ratio includes identifying the target recycle ratio based on an exponential moving average smoothing function by tracking a current recycle ratio.

5. The method as claimed in claim 1 wherein identifying a target recycle ratio includes identifying the target recycle ratio based on a smoothing feedback loop that compares a current recycle ratio to a target recycle ratio.

6. The method as claimed in claim 1 wherein identifying a target recycle ratio includes identifying the target recycle ratio based on a recycle ratio as a function of a reciprocal of a write amplification.

7. The method as claimed in claim 1 wherein identifying a target recycle ratio includes identifying the target recycle ratio based on a smoothing feedback loop when the at least one host write is not scheduled and a current recycle ratio is greater than the target recycle ratio.

8. A storage control system for controlling operation of a non-volatile memory device coupled to the storage control system, the storage control system comprising:

a recycle write queue for providing at least one recycle write;

a host write queue for providing at least one host write; and

a memory controller coupled to the memory device, the memory controller having one or more processors and including a scheduler module, coupled to the recycle write queue and the host write queue, for;

identifying a target recycle ratio in accordance with a current size of a spare pool of erased non-volatile memory blocks available to be written to, wherein the target recycle ratio is a targeted ratio of recycling page writes to host page writes;

placing the at least one recycle write and the at least one host write in a write operation queue in accordance with the target recycle ratio;

dispatching the at least one recycle write and the at least one host write from the write operation queue for writing data to the non-volatile memory device coupled to the storage control system;

during operation of the storage control system, updating the target recycle ratio in accordance with a change in the current size of the spare pool; and

after updating the target recycle ratio;

placing one or more recycle writes and one or more host writes in the write operation queue in accordance with the updated target recycle ratio; and

dispatching the one or more recycle writes and the one or more host writes from the write operation queue for writing data to the memory device.

9. The system as claimed in claim 8 wherein the scheduler module is for increasing the target recycle ratio in accordance with a decrease in size of the spare pool or decreasing the target recycle ratio in accordance with an increase in size of the spare pool.

10. The system as claimed in claim 8 wherein the scheduler module is for dynamically determining a first steady-state recycle ratio in a first steady state of the storage control system with respect to number of recycle write operations that are performed per host page write operation;

and wherein the scheduler module is also for detecting a change in the current size of the spare pool that satisfies predefined criteria, and in response to detecting the change in the current size of the spare pool that satisfies the predefined criteria, updating the target recycle ratio to a second steady-state recycle ratio in a second steady state of the storage control system with respect to number of recycle write operations that are performed per host page write operation, wherein the second steady-state recycle ratio is different from the first steady-state recycle ratio.

11. The system as claimed in claim 8 wherein the scheduler is for identifying the target recycle ratio based on an exponential moving average smoothing function by tracking a current recycle ratio.

12. The system as claimed in claim 8 wherein the scheduler is for identifying the target recycle ratio based on a smoothing feedback loop that compares a current recycle ratio to a target recycle ratio.

13. The system as claimed in claim 8 wherein the scheduler is for identifying the target recycle ratio based on a recycle ratio as a function of a reciprocal of a write amplification.

14. The system as claimed in claim 8 wherein the scheduler is for identifying the target recycle ratio based on an exponential moving average smoothing function by tracking a current recycle ratio with a subtraction module, a multiplication module, and an addition module.

15. The system as claimed in claim 8 wherein the scheduler is for identifying the target recycle ratio based on a smoothing feedback loop when the at least one host write is not scheduled and a current recycle ratio is greater than the target recycle ratio.