MLC Flash Memory Backup Block Data Recovery
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Solution Overview
Problem
NAND flash memory in Multi-Level Cell (MLC) flash devices faces limitations such as short lifetime, high error correction requirements, and data loss due to non-adjacent memory page addresses leading to errors during programming, especially when power is disrupted.
Innovation Solution
An electronic storage device with a first memory segment and a second backup segment, where information is written and stored through separate signal channels, and a control unit ensures data backup after writing and erasure, utilizing a Backup Block to restore data in case of errors, and recycling Backup Blocks to optimize storage space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If information is written into LSB memory page first, then MSB memory page, then programming order can be followed, but power disruption during MSB programming causes data loss in both pages
Solution Approach 1:
The patent applies preliminary action by writing data to the LSB memory page first, establishing a stable base before proceeding to the MSB memory page. This sequential approach ensures that if power disruption occurs during MSB programming, the LSB data remains intact and can be used to recover the complete information pair.
Solution Approach 2:
The patent implements copying by creating redundant copies of data across paired memory pages (LSB and MSB). The control unit writes the same information pair to both pages, and in case of programming errors or power disruption, the intact copy can be used to restore the lost data, ensuring data safety.
2Reliability
If Backup Block is used to restore data after error, then data safety is improved, but storage space is consumed
Solution Approach 1:
The patent applies discarding and recovering by using the Backup Block to store redundant data during programming operations. When programming errors occur or power disruption happens, the control unit recovers the lost data from the Backup Block. After successful recovery, the Backup Block is discarded or reused for new data, optimizing storage space while maintaining data safety.
3Quantity of substance
If MLC flash memory is used to increase capacity, then storage capacity is improved, but programming errors and data loss risk increase
Solution Approach 1:
The patent applies segmentation by dividing the MLC flash memory into distinct paired memory pages (LSB and MSB) and implementing separate control mechanisms for each page. This segmentation allows the control unit to manage programming operations independently for each page, reducing the propagation of programming errors and improving overall programming accuracy while maintaining high storage capacity.
Data Source
AI summary
An electronic storage device includes a first memory segment having at least one source block to store information, a second memory segment having at least one backup block corresponding to the source block to make a backup of the information in a LSB memory page of the source block and a control unit connecting with said first memory segment and second memory segment. The control unit reads/writes the first memory segment and second memory segment through two different signal channels respectively. The information can be simultaneously written into the first and second memory segment to get a backup of the information so that the information can be stored safely. The control unit recycles the backup block of the second memory segment not only after the source block of the first memory segment entirely finishes writing the information but also after the source block is erased up in order to release the storage space of the backup block.