Flash Memory Controller Wear Synchronization for Data Accuracy
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Solution Overview
Problem
Flash devices experience incorrect data determination due to electron leakage over time, causing shifts in threshold voltages, which leads to misinterpretation of stored data when using fixed decision voltages in existing methods.
Innovation Solution
The method involves dividing the storage array into specific and user storage units, ensuring they have the same wear and data storage features, and dynamically adjusting decision voltages based on the specific data to match the user data's storage conditions, thereby reducing incorrect data determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a preset decision voltage is used to read data from flash storage units, then the reading operation is simple and fast, but incorrect data determination occurs due to threshold voltage shifts caused by electron leakage over time
Solution Approach 1:
The patent applies preliminary action by performing a wear operation on a specific storage unit before using it to determine the decision voltage. This pre-conditioning ensures the storage unit has experienced similar wear characteristics to the user storage units, making its threshold voltage shift behavior representative for accurate decision voltage determination
Solution Approach 2:
The patent uses a specific storage unit as a copy or model of the user storage units. By subjecting this specific unit to wear operations and using its threshold voltage characteristics to determine the decision voltage, the system creates a representative model that captures the wear-induced threshold shifts without affecting the actual user data
2Reliability
If the threshold voltage of storage units is monitored and adjusted dynamically, then data determination accuracy is improved, but the complexity of the reading operation increases
Solution Approach 1:
The patent changes the parameter being monitored from the threshold voltage of user storage units to the threshold voltage of a specific storage unit that has been subjected to wear operations. This parameter substitution maintains accuracy while simplifying the process, as the specific unit's characteristics are used to determine the decision voltage without requiring continuous monitoring of user data storage units
3Measurement precision
If wear operations are performed on specific storage units to match user storage unit characteristics, then the decision voltage determination becomes more accurate, but additional operations and time are required
Solution Approach 1:
The wear operation on the specific storage unit is performed in advance, before the actual data reading operations. This preliminary conditioning ensures that when the decision voltage needs to be determined, the specific storage unit already has the appropriate wear characteristics, eliminating the need for time-consuming operations during critical read paths
Data Source
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AI summary
A flash device access method, apparatus, and system are provided. A flash device includes a controller and a storage array. The method includes: dividing the storage array into a specific storage unit and a user storage unit (S21), so that a storage feature of the specific storage unit is the same as that of the user storage unit (S22); writing, by the controller, specific data into the specific storage unit (S23); reading, by the controller, the specific data stored in the specific storage unit (S24); determining, by the controller, a decision voltage Vread based on the read specific data (S25); and reading, by the controller by using the determined decision voltage Vread, the user data stored in the user storage unit (S26). Incorrect determining of the data stored in the flash device may be reduced by using the access method, apparatus, and system.