Method and apparatus for flash cache management

• US 9,177,670 B1
• Filed: 09/30/2013
• Issued: 11/03/2015
• Est. Priority Date: 09/30/2013
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Derbeko, Philip, Benhanokh, Zvi Gabriel, Natanzon, Assaf, Don, Arieh, Eyal, Anat, Veprinsky, Alexandr
• Primary Examiner(s): TU, CHRISTINE TRINH LE
• Application Number:
  US14/041,290
• Time in Patent Office: 764 Days
• Field of Search: 714/704, 714/718, 714/745, 714/773, 714/6.32, 714/6.1, 714/42, 365/201, 365/200, 365/204, 365/218, 365/189.2, 365/189.09, 711/113, 711/111, 711/100
• US Class Current: 1/1
• CPC Class Codes: G06F 11/0706 the processing taking place on a specific hardware platform or in a specific software environment
• CPC Class Codes: G11C 16/16 for erasing blocks, e.g. arrays, words, groups
• CPC Class Codes: G11C 16/26 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 29/08 Functional testing, e.g. testing during refresh, power-on self testing [POST] or distributed testing

Abstract

Example embodiments of the present invention relate to a method and a system for improving performance of flash cache memory, such as in a host of a storage environment, for example, by preventing a cache cell from reaching an operation limit. The method includes determining that a number of operations to a first cell of a flash memory has reached a threshold and managing the flash memory according to the determination to prevent a failure of a second cell of the flash memory.

Claims

1. A method comprising:

determining that a number of operations to a first cell of a flash memory has reached a threshold; and

managing the flash memory according to the determination to prevent a failure of a second cell of the flash memory.

2. The method of claim 1 wherein the flash memory is flash cache memory.

3. The method of claim 1 wherein the threshold is below the threshold of operations to the first cell that would cause the failure of the second cell.

4. The method of claim 1 wherein managing the flash memory according to the determination to prevent a failure of a second cell of the flash memory comprises evicting data stored in the first cell from the flash memory.

5. The method of claim 4 further comprising:

determining that the data previously cached in the first cell is no longer cached at the first cell; and

recaching the data previously cached in the first cell in a third cell of the flash cache memory.

6. The method of claim 5 wherein recaching the data previously cached in the first cell in a third cell of the flash cache memory comprises:

reading the data from a storage device storing the data previously cached in the first cell; and

caching the data read from the storage device in the third cell.

7. The method of claim 6 further comprising:

erasing a page of the flash cache memory including the first cell; and

caching new data to the first cell.

8. The method of claim 4 wherein managing the flash memory according to the determination to prevent a failure of a second cell of the flash memory further comprises offloading cache management to a cache management system.

9. The method of claim 8 further comprising:

determining, by the cache management system, that the data previously cached in the first cell is no longer cached at the first cell; and

recaching, by the cache management system, the data previously cached in the first cell in a third cell of the flash cache memory.

10. The method of claim 8 wherein offloading cache management to a cache management system comprises:

performing a registration operation with the cache management system; and

notifying the cache management system of the determination of the reached threshold.

11. A system comprising:

flash memory;

a counter module configured to determine that a number of operations to a first cell of the flash memory has reached a threshold; and

a manager module configured to manage the flash memory according to the determination to prevent a failure of a second cell of the flash memory.

12. The system of claim 11 wherein the flash memory is flash cache memory.

13. The system of claim 11 wherein the threshold is below the threshold of operations to the first cell that would cause the failure of the second cell.

14. The system of claim 11 wherein the manager module is further configured to evict data stored in the first cell from the flash memory.

15. The system of claim 14 further comprising a cache manager configured to determine that the data previously cached in the first cell is no longer cached at the first cell and recache the data previously cached in the first cell in a third cell of the flash cache memory.

16. The system of claim 15 wherein the cache manager is further configured to read the data from a storage device storing the data previously cached in the first cell and cache the data read from the storage device in the third cell.

17. The system of claim 16 wherein the cache manager is further configured to erase a page of the flash cache memory including the first cell and cache new data to the first cell.

18. The system of claim 15 wherein the manager module is further configured to offload cache management to the cache manager.

19. The system of claim 18 wherein the manager module is further configured to perform a registration operation with the cache manager and notify the cache manager of the determination of the reached threshold.

20. A computer program product including a nontransitory computer readable storage medium storing computer program code comprising:

computer program code for determining that a number of operations to a first cell of a flash memory has reached a threshold; and

computer program code for managing the flash memory according to the determination to prevent a failure of a second cell of the flash memory.