Storage Mapping Table Maintenance in NAND Flash via DRAM Grouping
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Solution Overview
Problem
Flash memory devices, particularly NAND flash devices, face inefficiencies in data write speed due to their serial access nature, requiring frequent updates to storage mapping tables, which can lead to poor performance and potential timeouts during data processing.
Innovation Solution
A method and apparatus for maintaining a storage mapping table by reading a group mapping table from the last page of a block, allocating data across multiple groups, and storing this information in DRAM, allowing for efficient data retrieval and updating, with a processing unit directing the access interface to store data in specified locations and rebuild the mapping table efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If storage mapping table updates are performed frequently in NAND flash devices, then data write speed can be improved, but system reliability deteriorates due to potential timeouts and performance degradation
Solution Approach 1:
The storage mapping table is divided into multiple groups, with each group stored in a separate DRAM buffer. This segmentation allows selective updating of individual groups without requiring complete table reconstruction, enabling faster updates while maintaining system stability through partial refresh operations.
Solution Approach 2:
The patent maintains a DRAM buffer that pre-loads and caches mapping table groups before they are needed for actual data writes. This preliminary action reduces the frequency of critical updates to the flash memory during active write operations, thereby improving reliability while maintaining write speed through the buffered data.
2Productivity
If the storage mapping table is maintained with high update frequency, then data access efficiency is improved, but loss of time increases due to repeated read-modify-write cycles
Solution Approach 1:
The patent combines the storage mapping table data with the actual data being written to the flash memory. By merging these operations, the system performs a single write operation that updates both the data and the mapping information simultaneously, eliminating separate read-modify-write cycles and reducing time loss.
Solution Approach 2:
The patent creates and maintains copies of the storage mapping table in DRAM buffers. These copies allow the system to perform updates in the buffer without immediately propagating changes back to the flash memory, significantly reducing the time required for mapping table maintenance while preserving data access efficiency.
3Productivity
If storage mapping table updates are performed frequently, then data write performance is improved, but device complexity increases due to additional management overhead
Solution Approach 1:
The patent implements self-service mechanisms where the flash memory controller automatically manages the storage mapping table updates without requiring external intervention. The system autonomously handles buffer management, update scheduling, and consistency maintenance, improving write performance while containing complexity within the controller rather than requiring complex external management.
Data Source
AI summary
A method for maintaining a storage mapping table. An access interface is directed to read a group mapping table from the last page of a block of a storage unit. The block is allocated to store data of a plurality of groups, each group stores information indicating which location in the storage unit stores data of an LBA (Logical Block Address) range, and the group mapping table stores information indicating which unit of the block stores the latest data of each group. The group mapping table is stored in a DRAM (Dynamic Random Access Memory). The access interface is directed to read data of each group from the storage unit according to the group mapping table. The data of each group is stored in a specified location of a storage mapping table of the DRAM.