Flash Memory Controller Leaping Linear Search for Last Used Page
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Solution Overview
Problem
Data storage devices, such as FLASH memory, face misjudgments when determining the last currently-used logical page due to abnormal power-offs, affecting subsequent data writing operations.
Innovation Solution
A data storage method that performs a linear search for logical pages, incrementally decreasing a predetermined value to identify the actual last currently-used page, and optionally uses binary search to confirm the last used page, ensuring accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional linear search is performed to detect the last currently-used logical page, then the search process is simple to implement, but the search time increases significantly when the last used page is at the bottom of the logical block
Solution Approach 1:
The patent divides the logical block into multiple sub-blocks and performs search operations on each sub-block separately. By segmenting the search space, the controller can quickly identify which sub-block contains the last used page and then perform a detailed search only within that sub-block, significantly reducing the total search time compared to a conventional linear search of the entire block.
Solution Approach 2:
The patent performs preliminary detection of sub-block boundaries and uses this information to guide the search process. By pre-organizing the logical block into sub-blocks and storing boundary information, the controller can jump directly to relevant sub-blocks during search operations, avoiding unnecessary inspections of unrelated areas and reducing overall search time.
2Measurement precision
If the controller performs a thorough search to accurately identify the last currently-used logical page, then the accuracy of detection is improved, but the complexity of the detection process increases
Solution Approach 1:
The patent segments the detection process into two stages: first detecting sub-block boundaries and then searching within specific sub-blocks. This segmentation maintains high detection accuracy by ensuring thorough search within relevant areas while reducing overall process complexity through structured organization and systematic search procedures.
Solution Approach 2:
The patent implements a dynamic search strategy that adapts based on detected information. The controller dynamically adjusts the search scope by identifying sub-block boundaries first, then concentrating search efforts only on sub-blocks that may contain the last used page. This dynamic approach maintains high accuracy while reducing complexity compared to static exhaustive search methods.
3Ease of manufacture
If the controller uses a fixed step size for searching logical pages, then the search process is simple to implement, but the search efficiency decreases when the last used page is located at different positions
Solution Approach 1:
The patent employs a dynamic search step size that varies based on the detected position and characteristics of logical pages. Instead of using a fixed step size, the controller adjusts the search increment dynamically - using larger steps when skipping through non-used pages and smaller steps when approaching potentially used pages. This dynamic adjustment maintains implementation simplicity while significantly improving search efficiency across different page distribution scenarios.
Data Source
AI summary
A data storage device utilized for storing a plurality of data, wherein the data storage device includes a memory and a controller. The memory includes a plurality of blocks, and each of the blocks includes a plurality of physical pages. The controller is coupled to the memory and maps the logical pages to the physical pages of the memory, and it performs a leaping linear search for the logical pages. The controller searches the Nth logical page of the logical pages according to a predetermined value N. N is a positive integer greater than 1. When the Nth logical page is a currently-used logical page, the controller incrementally decreases the predetermined value N to keep searching the logical pages until a non-currently-used logical page is detected.