Method, system and computer readable medium for copy back

• US 9,063,878 B2
• Filed: 10/28/2011
• Issued: 06/23/2015
• Est. Priority Date: 11/03/2010
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: DensBits Technologies Ltd. (Broadcom, Inc.)
• Inventors: Sabbag, Erez, Weingarten, Hanan
• Primary Examiner(s): Faal, Baboucarr
• Application Number:
  US13/284,794
• Publication Number:
  US 20120110250A1
• Time in Patent Office: 1,334 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 11/5671 using charge trapping in an insulator
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators

Abstract

Systems, computer readable media and methods for updating a flash memory device involve procedures for transferring, from a flash memory device to an external controller, only a portion of a data entity; and determining, by the external controller, based upon the portion of the data entity, whether to complete a copy back operation of the data entity or to correct errors of the data entity. If it is determined to correct errors of the data entity, then the procedure includes (a) completing a transfer of the data entity to the external controller; (b) error correcting the data entity to provide an amended data entity; and (c) writing the amended data entity to the flash memory device. If, however, it is determined to complete the copy back operation then the procedures includes completing the copy back operation of the data entity by transferring the data entity within the flash memory device.

Claims

1. A method for updating a flash memory device, the method comprising:

transferring, from a flash memory device to an external controller, a portion of a data entity without transferring the data entity in its entirety;

determining, by the external controller, based upon the portion of the data entity, whether to complete a copy back operation of the data entity or to correct errors of the data entity;

if it is determined to correct errors of the data entity;

completing a transfer of the data entity to the external controller;

error correcting the data entity to provide an amended data entity; and

writing the amended data entity to the flash memory device;

wherein the completing of the transfer of the data entity to the external controller comprises reading the data entity using a second set of read thresholds that differs from a first set of read thresholds;

if it is determined to complete the copy back operation;

completing the copy back operation of the data entity by transferring the data entity within the flash memory device.

2. The method according to claim 1, further comprising initiating the copy back operation after a completion of the determining.

3. The method according to claim 1, wherein the transferring comprises transferring at least the portion of the data entity;

and wherein the method further comprises initiating the copy back operation before completion of the determining.

4. The method according to claim 3, further comprising:

completing a transfer of a fraction of the data entity to a first flash memory fraction before the completion of the determining; and

declaring the first flash memory fraction as storing invalid data if it is determined to correct errors of the data entity.

5. The method according to claim 3, comprising:

completing a transfer of a fraction of the data entity to a first flash memory fraction before the completion of the determining; and

writing the amended data entity to a second flash memory fraction that differs from the first flash memory fraction.

6. The method according to claim 1, wherein the method comprises soft decoding the data entity by the external controller, if it is determined to correct errors of the data entity.

7. The method according to claim 1, wherein the determining comprises:

decoding multiple sub-sets of the portion of the data entity by at least one error correction code to provide multiple results; and

determining whether to complete the copy back operation or to correct errors of the data entity based on the multiple results.

8. The method according to claim 1, wherein the determining comprises applying an error detection code or an error correction code that differs from an error correction code applied by the external controller during the error correcting of the data entity.

9. The method according to claim 1, comprising transferring the data entity to a flash memory space within the flash memory device;

and prioritizing the flash memory space for wear-leveling.

10. The method according to claim 1, wherein the data entity is stored at a flash memory space;

and wherein the method comprises invoking the transferring and the determining based on at least one parameter of (a) a number of erase cycle that the flash memory space has undergone;

(b) an age of the flash memory space; and

(c) errors detected in reading attempts of similar flash memory spaces.

11. The method according to claim 1, wherein the determining is responsive to a load level of the flash memory device.

12. The method according to claim 1, wherein the portion of the data entity comprises redundancy bits that represent a number of copy back operations that were applied on the data entity after a last error correction operation was applied on the data entity;

and wherein the determining is responsive to the number.

13. The method according to claim 12, comprising updating the number in response to the determining.

14. The method according to claim 12, comprising storing the redundancy bits within a register of the flash memory device;

receiving from the external controller an updated value of the redundancy bits that reflects an update of the number; and

programming the redundancy bits to a flash memory space.

15. A method for updating a flash memory device, the method comprising;

transferring, from a flash memory device to an external controller, a portion of a data entity;

determining, by the external controller, based upon the portion of the data entity, whether to complete a copy back operation of the data entity or to correct errors of the data entity;

if it is determined to correct errors of the data entity;

completing a transfer of the data entity to the external controller;

error correcting the data entity to provide an amended data entity; and

writing the amended data entity to the flash memory device;

if it is determined to complete the copy back operation;

completing the copy back operation of the data entity by transferring the data entity within the flash memory device;

wherein the determining comprises performing a modulo test of the portion of the data entity.

16. A system comprising:

a flash memory device; and

an external controller;

wherein the external controller is arranged to;

read a portion of a data entity from the flash memory device;

determine, based upon the portion of the data entity, whether to complete a copy back operation of the data entity or to correct errors of the data entity;

wherein if it is determined to correct errors of the data entity, the external controller is arranged to;

complete a read operation of the data entity from the flash memory device;

error correct the data entity to provide an amended data entity; and

write the amended data entity to the flash memory device;

otherwise, if it is determined to complete the copy back operation, the flash memory device is arranged to complete the copy back operation of the data entity by transferring the data entity within the flash memory device;

wherein the external controller is arranged to determine whether to complete the copy back operation by performing a modulo test of the portion of the data entity.

17. A system comprising:

a flash memory device; and

an external controller;

wherein the flash memory device is arranged to read a portion of a data entity using a first set of read thresholds; and

transfer to the external controller, the portion of the data entity without transferring the data entity in its entirety;

wherein the external controller is arranged to perform a determination, based upon the portion of the data entity, whether to complete a copy back operation of the data entity or to correct errors of the data entity;

if it is determined to correct errors of the data entity then the flash memory device is arranged to reading the data entity using a second set of read thresholds that differs from the first set of read thresholds and complete a transfer of the data entity to the external controller; and

wherein the external controller is arranged to error correct the data entity to provide an amended data entity; and

write the amended data entity to the flash memory device;

if it is determined to complete the copy back operation then the flash memory device is arranged to complete the copy back operation of the data entity by transferring the data entity within the flash memory device.

18. The system according to claim 17 wherein the flash memory device is arranged to initiate the copy back operation after a completion of the determination.

19. The system according to claim 17 wherein the flash memory device is arranged to initiate the copy back operation before completion of the determination.

20. The system according to claim 17 wherein the flash memory device is arranged to complete a transfer of a fraction of the data entity to a first flash memory fraction before a completion of the determination;

and wherein the external controller is arranged to declare the first flash memory fraction as storing invalid data if it is determined to correct errors of the data entity.

21. The system according to claim 17 wherein the flash memory device is arranged to write the amended data entity to a second flash memory fraction that differs from the first flash memory fraction.

22. The system according to claim 17 wherein the external controller is arranged to soft decode the data entity if it is determined to correct errors of the data entity.

23. The system according to claim 17 wherein the external controller is arranged to decode multiple sub-sets of the portion of the data entity by at least one error correction code to provide multiple results;

and determine whether to complete the copy back operation or to correct errors of the data entity based on the multiple results.

24. The system according to claim 17 wherein the external controller is arranged to apply an error detection code or an error correction code that differs from an error correction code applied by the external controller during the error correcting of the data entity.

25. The system according to claim 17 wherein the flash memory device is arranged to transfer the data entity to a flash memory space within the flash memory device;

and prioritize the flash memory space for wear-leveling.

26. The system according to claim 17, wherein the data entity is stored at a flash memory space;

and wherein the external controller is arranged to invoke the transfer of the portion of the data unit and the determination based on at least one parameter of (a) a number of erase cycle that the flash memory space has undergone;

(b) an age of the flash memory space; and

(c) errors detected in reading attempts of similar flash memory spaces.

27. The system according to claim 17, wherein the determination is responsive to a load level of the flash memory device.

28. The system according to claim 17, wherein the portion of the data entity comprises redundancy bits that represent a number of copy back operations that were applied on the data entity after a last error correction operation was applied on the data entity;

and wherein the determination is responsive to the number.

29. The system according to claim 28, wherein the external controller is arranged to update the number in response to the determination.

30. The system according to claim 28, wherein the flash memory device is arranged to store the redundancy bits within a register of the flash memory device;

receive from the external controller an updated value of the redundancy bits that reflects an update of the number; and

program the redundancy bits to a flash memory space.