SSD Mapping Table Reconstruction via Logical Address Offsets
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Solution Overview
Problem
The process of reconstructing a mapping table in a Solid State Drive (SSD) is time-consuming due to the need for full scans of all physical pages when the mapping table is lost, requiring numerous read operations.
Innovation Solution
The method involves scanning starting from the last physical page of a corresponding block, reading a logical address and multiple logical address offsets from the data area of each physical page, and reconstructing the mapping relationship between logical and physical addresses, thereby reducing the number of full scans needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spare area of each physical page is used to store logical address information, then the mapping relationship can be recovered, but the number of read operations increases to 16000 times
Solution Approach 1:
The patent stores logical address information in advance in the data area of physical pages during normal write operations. When mapping table reconstruction is needed, this pre-stored information is directly utilized, eliminating the need for extensive scanning operations. This preliminary preparation significantly reduces reconstruction time while ensuring reliability.
Solution Approach 2:
The patent changes the storage dimension by moving logical address information from the traditional spare area to the data area of physical pages. This dimensional shift allows for more efficient storage and retrieval, reducing the number of read operations from 16000 times to approximately 2000 times during reconstruction.
2Reliability
If the entire SSD is scanned to read data of each physical page, then complete mapping table can be established, but the reconstruction process takes a lot of time
Solution Approach 1:
The patent extracts essential logical address information from the full physical page data and stores it separately in the data area. During reconstruction, only this extracted information needs to be read, rather than scanning entire physical pages. This extraction principle reduces the reconstruction workload from 16000 read operations to about 2000 read operations.
Solution Approach 2:
The patent performs preliminary extraction and storage of logical address information during normal write operations. This advance preparation ensures that during reconstruction, the system only needs to retrieve pre-processed data, dramatically improving reconstruction efficiency while maintaining complete mapping table accuracy.
3Productivity
If N logical address offsets are stored in the data area, then the number of scans is reduced to approximately 2000 times, but the storage structure becomes more complex
Solution Approach 1:
The patent changes the storage parameters by storing not only logical addresses but also N logical address offsets in the data area. This parameter expansion allows the system to skip N physical pages at once during reconstruction, reducing scan operations from 16000 to approximately 2000 times. The increased storage capacity of the data area accommodates this additional information efficiently.
Data Source
AI summary
A method and an apparatus of mapping table reconstruction based on a SSD, and a computer device are disclosed by the present application, and the method includes: acquiring the mapping table reconstruction request based on the SSD; scanning starting from the last physical page of the corresponding physical block according to the mapping table reconstruction request based on the SSD; reading the corresponding logical address and N logical address offsets from a data area of the current physical page, where N is the positive integer greater than 1; acquiring logical addresses corresponding to N adjacent pages in sequence according to the logical address corresponding to the current physical page and the N logical address offsets; reconstructing a mapping relationship between logical addresses and physical addresses according to the logical address corresponding to the current physical page and the logical addresses corresponding to the N adjacent pages.