Solving MLC NAND paired page program using reduced spatial redundancy
Reduced spatial redundancy of lower bits data provides data protection for a flash memory having MLC NAND devices operated in page mode. An interrupted write operation of most significant bit pages can corrupt previously written data in lower bit pages. The lower bits redundant memory assists in restoring the data, using less than a full back up storage.
1. A method of managing a memory, the method comprising
configuring a first memory and a second memory,
wherein the first memory and the second memory each comprises a plurality of multi-level cell (MLC) memory cells,
wherein each MLC memory cell comprises at least a least significant bit (LSB) and a most significant bit (MSB);
copying first data from the first memory to the second memory,
wherein the first data comprise multiple LSB data and exclude all of the MSB data of the MLC memory cells of the first memory,
wherein a first portion of the first data is copied to one or more LSBs of the MLC memory cells of the second memory,
wherein a second portion of the first data is copied to one or more MSBs of the MLC memory cells of the second memory;
writing second data to at least a MSB of the MLC memory cells of the first memory after copying the first data.
2. The method as in claim 1 wherein the first memory is configured from a fabricated memory having a main memory portion and a repair portion, wherein the repair portion is configured to replace a portion of the main memory portion that are defective in the fabrication process, and wherein the second memory is formed from the repair portion.
3. The method as in claim 1 wherein the first memory comprises a portion of the memory, and wherein the second memory comprises a remaining portion of the memory.
4. The method as in claim 1 further comprising
protecting data in the second memory to prevent the second memory from being changed when performing the writing operation to the first memory.
5. The method as in claim 1 further comprising
storing a write status of the writing operation to the first memory.
6. The method as in claim 1 further comprising
restoring data from the second memory to the multiple LSB data and excluding all of the MSB data of the MLC memory cells of the first memory,
wherein the restoring operation is performed during a power up of a data storage module when an interrupted writing operation is detected.
7. A data storage system comprising
a first memory,
wherein the first memory comprises a plurality of first multi-level cell (MLC) memory cells,
wherein each first MLC memory cell comprises at least a least significant bit (LSB) and a most significant bit (MSB),
wherein the first memory is configured for page mode data management;
a second memory,
wherein the second memory comprises a plurality of second multi-level cell (MLC) memory cells,
wherein each second MLC memory cell comprises at least a least significant bit (LSB) and a most significant bit (MSB),
wherein the second memory is configured to store a copy of first data of the first memory,
wherein the first data comprise multiple LSB data and exclude all of the MSB data of the first MLC memory cells,
wherein a first portion of the first data is configured to be stored in one or more LSBs of the second MLC memory cells,
wherein a second portion of the first data is configured to be stored in one or more MSBs of the second MLC memory cells.
8. The data storage system as in claim 7 wherein the page mode data management comprises a storing of the LSBs and MSBs of the MLC memory cells in separate LSB pages and MSB pages, respectively.
9. The data storage system as in claim 7 wherein the first memory is configured from a fabricated memory having a main memory portion and a repair portion, wherein the repair portion is configured to replace a portion of the main memory portion that are defective in the fabrication process, and wherein the second memory is formed from the repair portion.
10. The data storage system as in claim 7 further comprising
a data saving module, wherein the data saving module is configured to activate a copy operation from the multiple LSB data of the MLC memory cells of the first memory to the second memory,
wherein the data saving module is configured to be activated before an writing operation to the first memory.
11. The data storage system as in claim 7 further comprising
a data protected module, wherein the data protected module is configured to enforce a mutually exclusive writing action to the first and second memories.
12. The data storage system as in claim 7 further comprising
a flag module, wherein the flag module is configured to store a write status of a write operation to the first memory.
13. The data storage system as in claim 7 further comprising
a restore module, wherein the restore module is configured to copy data from the second memory to the multiple LSBs of the MLC memory cells of the first memory, wherein the restore module is configured to be activated during a power up of a data storage module when an interrupted writing operation is detected.
14. The data storage system as in claim 7 further comprising
a controller coupled to the first and second memories, wherein the controller is configured to provide a data management system for operating the first and second memories.
15. The data storage system as in claim 7 further comprising
an interface coupled to the first and second memories, wherein the interface is configured to receive and send commands from an external processor for managing the first and second memories.
16. The data storage system as in claim 7 further comprising
a data management system coupled to the first and second memories,
wherein the data management system is configured to activate a copy operation from the multiple LSB data of the MLC memory cells of the first memory to the second memory before a writing operation to the first memory,
wherein the data management system is configured to activate a mutually exclusive writing action to the first and second memories,
wherein the data management system is configured to store a write status of the write operation to the first memory,
wherein the data management system is configured to copy data from the second memory to the multiple LSBs of the MLC memory cells of the first memory during a power up of a data storage module when an interrupted writing operation is detected.
17. A non-transitory computer readable storage medium having a computer readable code executed by a processor for improving data reliability in a data storage system, wherein the data storage system comprises a first memory and a second memory, wherein the first memory and the second memory each comprises a plurality of multi-level cell (MLC) memory cells, wherein each MLC memory cell comprises at least a least significant bit (LSB) and a most significant bit (MSB), the computer readable code comprising:
program code for copying first data from the first memory to the second memory,
wherein the first data comprise multiple LSB data and exclude all of the MSB data of the MLC memory cells of the first memory,
wherein a first portion of the first data is configured to be copied to one or more LSBs of the MLC memory cells of the second memory,
wherein a second portion of the first data is configured to be copied to one or more MSBs of the MLC memory cells of the second memory;
program code for writing second data to at least a MSB of the MLC memory cells.
18. The computer readable storage medium as in claim 17 ,
wherein the computer readable code further comprising
program code for protecting data in the second memory to prevent the second memory from being changed when performing the writing operation to the first memory.
19. The computer readable storage medium as in claim 17 ,
wherein the computer readable code further comprising
program code for restoring data from the second memory to the multiple LSB data and excluding all of the MSB data of the MLC memory cells of the first memory, wherein a restoring operation is performed during a power up of the data storage module when an interrupted writing operation is detected.
20. The computer readable storage medium as in claim 17 , wherein the computer readable code further comprising
program code for copying the first data from the first memory to a repair portion,
wherein the first memory is configured from a fabricated memory having a main memory portion and the repair portion, wherein the repair portion is configured to replace a portion of the main memory portion that are defective in the fabrication process.