Open block handling to reduce write errors

Patent metadata

Field	Value
Publication number	US-9933963-B1
Application number	US-201715446576-A
Country	US
Kind code	B1
Filing date	Mar 1, 2017
Priority date	Mar 1, 2017
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

Systems and methods presented herein provide for open block handling of an SSD. In one embodiment, an SSD includes a buffer, and an MLC flash device. The SSD also includes a controller operable to write data in the buffer based on an Input/Output (I/O) request (e.g., from a host), to begin copying the data from the buffer to a block of the MLC flash device, to copy a portion of the data associated with open word lines of the block to another location in the buffer after a power cycle, and to update a lookup table for the copied portion of the data with the other location so that the copied portion of the data can be accessed via a subsequent I/O request.

First claim

What is claimed is:

1. A Solid State Drive (SSD), comprising:
a buffer;
a multi-level cell (MLC) flash device; and
a controller operable to write data in the buffer based on an Input/Output (I/O) request, to begin copying the data from the buffer to a block of the MLC flash device, to copy a portion of the data associated with open word lines of the block to another location in the buffer after a power cycle, and to update a lookup table for the copied portion of the data with the other location so that the copied portion of the data can be accessed via a subsequent I/O request.

2. The SSD of claim 1 , wherein:
the controller is further operable to abandon the open word lines of the MLC flash device after the power cycle until garbage collection is performed.

3. The SSD of claim 1 , wherein:
the controller is further operable to generate a pointer to the other location in the lookup table, and to direct a read I/O request for the copied portion of the data to the other location of the buffer using the pointer.

4. The SSD of claim 1 , wherein:
the controller is further operable to copy the portion of the data to another location of the MLC flash device after the power cycle.

5. The SSD of claim 4 , wherein:
the controller is further operable to generate a pointer to the other location of the MLC flash device, and to direct a read I/O request for the copied portion of the data to the other location of the MLC flash device using the pointer.

6. The SSD of claim 1 , wherein:
the buffer comprises a single level cell device.

7. The SSD of claim 1 , wherein:
the controller is further operable to close the block of the MLC device after the power cycle, and to retain fully programmed data in the block so that the fully programmed data in the block can be accessed via a subsequent I/O request.

8. A method operable with a controller of a Solid State Drive (SSD), the method comprising:
writing data in a buffer based on an Input/Output (I/O) request;
begin copying the data from the buffer to a block of a multi-level cell (MLC) flash device;
copying a portion of the data associated with open word lines of the block to another location in the buffer after a power cycle; and
updating a lookup table for the copied portion of the data with the other location so that the copied portion of the data can be accessed via a subsequent I/O request.

9. The method of claim 8 , further comprising:
abandoning the open word lines of the MLC flash device after the power cycle until garbage collection is performed.

10. The method of claim 8 , further comprising:
generating a pointer to the other location in the lookup table; and
directing a read I/O request for the copied portion of the data to the other location of the buffer using the pointer.

11. The method of claim 8 , further comprising:
copying the portion of the data to another location of the MLC flash device after the power cycle.

12. The method of claim 11 , further comprising:
generating a pointer to the other location of the MLC flash device; and
directing a read I/O request for the copied portion of the data to the other location of the MLC flash device using the pointer.

13. The method of claim 8 , wherein:
the buffer comprises a single level cell device.

14. The method of claim 8 , further comprising:
closing the block of the MLC device after the power cycle; and
retaining fully programmed data in the block so that the fully programmed data in the block can be accessed via a subsequent I/O request.

15. A non-transitory computer readable medium comprising instructions that, when executed by a controller of a Solid State Drive (SSD), direct the controller to:
write data in a buffer based on an Input/Output (I/O) request;
begin copying the data from the buffer to a block of a multi-level cell (MLC) flash device;
copy a portion of the data associated with open word lines of the block to another location in the buffer after a power cycle; and
update a lookup table for the copied portion of the data with the other location so that the copied portion of the data can be accessed via a subsequent I/O request.

16. The computer readable medium of claim 15 , further comprising instructions that direct the controller to:
abandon the open word lines of the MLC flash device after the power cycle until garbage collection is performed.

17. The computer readable medium of claim 15 , further comprising instructions that direct the controller to:
generate a pointer to the other location in the lookup table; and
direct a read I/O request for the copied portion of the data to the other location of the buffer using the pointer.

18. The computer readable medium of claim 15 , further comprising instructions that direct the controller to:
copy the portion of the data to another location of the MLC flash device after the power cycle.

19. The computer readable medium of claim 18 , further comprising instructions that direct the controller to:
generate a pointer to the other location of the MLC flash device; and
direct a read I/O request for the copied portion of the data to the other location of the MLC flash device using the pointer.

20. The computer readable medium of claim 15 , wherein:
the buffer comprises a single level cell device.

21. The computer readable medium of claim 15 , further comprising instructions that direct the controller to:
close the block of the MLC device after the power cycle; and
to retain fully programmed data in the block so that the fully programmed data in the block can be accessed via a subsequent I/O request.

Assignees

• Seagate Technology Llc
• Seagate Technology

Inventors

• Alhussien Abdel Hakim
• Tang Alex
• Baryudin Leonid
• Haratsch Erich Franz

Classifications

• G06F3/065

  Replication mechanisms · CPC title

• G06F3/0679

  Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP] · CPC title

• G06F2212/702

  Conservative garbage collection · CPC title

• G06F3/0625

  Power saving in storage systems · CPC title

• G06F3/0659

  Command handling arrangements, e.g. command buffers, queues, command scheduling · CPC title