Forward error correction with parallel error detection for flash memories
View Patent ↗Methods, systems, and devices are described for forward error correction for flash memory. Encoded data from flash memory may be used to generate a number of data streams. At each of a number of error detection sub-modules operating in parallel, a different one of the data streams is processed. Each error detection sub-module may detect whether a portion of the respective received stream contains an error, and forward the portion to an error correction module. The error correction module, physically separate from the error detection sub-modules, may correct the forwarded portions of the respective received streams containing an error. The age and error rate associated with the flash memory may be monitored, and a coding rate or other aspects may be dynamically adapted to account for these factors.
1. A method comprising:
encoding data using forward error correction coding;
storing the encoded data in a flash memory;
retrieving the encoded data stored in the flash memory to generate a data stream;
processing, using at least a first error correction sub-module, the data stream to correct errors in the data stream associated with the flash memory;
monitoring a metric of the flash memory while repeating the encoding, the storing, the retrieving and the processing, wherein the metric represents memory performance degradation of the flash memory;
determining that the monitored metric exceeds a threshold;
in response to the determination, modifying the forward error correction coding for use in subsequently encoding data for storage in the flash memory; and
in response to the determination, powering-up, from an inactive mode, a second error correction sub-module arranged in parallel with the first error correction sub-module for subsequent data stream processing.
2. The method of claim 1 , wherein the modifying comprises changing a coding rate of the forward error correction coding.
3. The method of claim 1 , wherein the modifying comprises implementing more robust forward error correction coding.
4. The method of claim 1 , wherein the metric is based at least in part on an aging of the flash memory.
5. The method of claim 4 , wherein the metric is based on one or more of a time since manufacture of the flash memory, a time since first use of the flash memory, and an amount of use of the flash memory.
6. The method of claim 1 , wherein the metric is based at least in part on an amount of errors corrected during the processing.
7. The method of claim 6 , wherein the metric is based on the amount of errors corrected over a period of time.
8. The method of claim 1 , wherein the retrieving, the processing and the monitoring are performed on a sector-by-sector basis of the flash memory.
9. The method of claim 1 , further comprising:
subsequently encoding data using the modified forward error correction coding; and
storing the subsequently encoded data in the flash memory.
10. The method of claim 9 , wherein the subsequently encoded data is stored in a sector of the flash memory different than that of said encoded data.
11. The method of claim 9 , further comprising:
retrieving the subsequently encoded data stored in the flash memory to generate a second data stream; and
processing, using at least the first error correction sub-module and the second error correction sub-module, the data stream to correct errors in the data stream associated with the flash memory.
12. The method of claim 1 , wherein the threshold is based at least in part on an amount of available memory within the flash memory.
13. A system comprising:
an encoder to encode data using forward error correction coding;
a flash memory to store the encoded data;
a decoder to retrieve the encoded data stored in the flash memory to generate a data stream, and to process the data stream to correct errors in the data stream associated with the flash memory using at least a first error correction sub-module; and
a controller to:
monitor a metric of the flash memory while repeating the encoding, the storing, the retrieving and the processing, wherein the metric represents memory performance degradation of the flash memory;
determine that the monitored metric exceeds a threshold;
in response to the determination, modify the forward error correction coding for use by the encoder in subsequently encoding data for storage in the flash memory; and
in response to the determination, powering-up, from an inactive mode, a second error correction sub-module arranged in parallel with the first error correction sub-module for subsequent data stream processing.
14. The system of claim 13 , wherein the controller changes a coding rate of the forward error correction coding to modify the forward error correction coding.
15. The system of claim 13 , wherein the controller implements more robust forward error correction coding to modify the forward error correction coding.
16. The system of claim 13 , wherein the metric is based at least in part on an aging of the flash memory.
17. The system of claim 16 , wherein the metric is based on one or more of a time since manufacture of the flash memory, a time since first use of the flash memory, and an amount of use of the flash memory.
18. The system of claim 13 , wherein the metric is based at least in part on an amount of errors corrected during the processing.
19. The system of claim 18 , wherein the metric is based on the amount of errors corrected over a period of time.
20. The system of claim 13 , wherein the decoder retrieves the encoded data and processes the data stream on a sector-by-sector basis of the flash memory, and the controller monitors the metric on a sector-by-sector basis of the flash memory.
21. The system of claim 13 , wherein:
the encoder subsequently encodes data using the modified forward error correction coding; and
the flash memory stores the subsequently encoded data in the flash memory.
22. The system of claim 21 , wherein the flash memory stores the subsequently encoded data in a sector different than that of said encoded data.
23. The system of claim 21 , wherein the decoder:
retrieves the subsequently encoded data stored in the flash memory to generate a second data stream; and
processes, using at least the first error correction sub-module and the second error correction sub-module, the data stream to correct errors in the data stream associated with the flash memory.
24. The system of claim 13 , wherein the threshold is based at least in part on an amount of available memory within the flash memory.