Flash Memory Controller Valid Data Identification After Power Failure
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Solution Overview
Problem
Flash memory storage devices face challenges in identifying valid data after a power failure, as the record table for mapping logical pages to physical pages may be lost or not updated in time, leading to uncertainty about where the latest valid data is stored when power is resumed.
Innovation Solution
A method and memory controller that record the address of the previous data for each logical page in the physical page of a substitute block from the spare area, ensuring that even after a power failure, the physical page containing the latest valid data can be identified by mapping logical blocks to physical blocks in the data area and spare area, preventing data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the memory storage device does not instantly move all valid data from the mother physical block to the child physical block or erase the mother physical block to increase writing speed, then data writing speed is improved, but the record table may be lost or not updated in time when power failure occurs, making it impossible to determine where the latest valid data is stored
Solution Approach 1:
The patent applies preliminary action by recording the address of the physical page containing previous data corresponding to each logical page before writing new data. This pre-recording mechanism ensures that when power failure occurs, the system can still identify where valid data is stored by checking these pre-recorded addresses, thus resolving the contradiction between writing speed and data validity identification reliability
Solution Approach 2:
The patent uses the address record of the physical page containing previous data as an intermediary mechanism. This intermediary record allows the system to trace and identify valid data locations without needing to maintain a complete updated record table, thus enabling reliable data identification while allowing asynchronous data movement operations for improved writing speed
2Productivity
If multiple child physical blocks are allowed to be mapped to the same logical page to make writing operations more efficient, then writing efficiency is improved, but physical pages from different physical blocks may be mapped to the same logical page, complicating the tracking of valid data locations
Solution Approach 1:
The patent extracts the essential information needed for data location tracking by recording only the address of the physical page containing previous data for each logical page. This extracted information serves as a sufficient indicator to identify valid data locations without requiring complex tracking of all mapping relationships, thus reducing device complexity while maintaining multi-child-block mapping capability for writing efficiency
Solution Approach 2:
The patent uses a simplified copying approach where instead of maintaining complex mapping relationships between logical pages and multiple physical pages, it copies and stores only the address of the physical page containing previous data. This copied address information is sufficient to identify valid data locations, simplifying the tracking mechanism while allowing multiple child physical blocks to be mapped to the same logical page
Data Source
AI summary
A memory storage device, a memory controller, and a method for identifying a valid data are provided. A rewritable non-volatile memory chip of the memory storage device includes physical blocks. Each of the physical blocks has physical pages. In the present method, logical blocks are configured and mapped to a portion of the physical blocks, wherein each of the logical blocks has logical pages. When a data to be written by a host system into a specific logical page is received, a substitute physical block is selected, the data is written into a specific physical page in the substitute physical block, and the address of a physical page in which a previous data corresponding to the specific logic page is written is recorded into the specific physical page. Thereby, a physical page containing the latest valid data can be identified among several physical pages corresponding to a same logical page.