Non-volatile Memory Partial Block Write Method
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Solution Overview
Problem
Conventional non-volatile memory devices experience reduced write speed when writing data smaller than the erase size of the flash memory, as they write data in units of the erase size, leading to inefficiencies in data management and longer write times.
Innovation Solution
The non-volatile memory device writes data in units of partial physical blocks, using an address conversion table to map logical addresses to physical and partial physical blocks, allowing data to be written in unwritten regions and ensuring erased blocks are available for subsequent writes, thus aligning the write unit with the host device's data write unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data is written in units of the erase size (128 KB), then the flash memory capacity utilization is improved, but the write speed deteriorates when writing data smaller than the erase size
Solution Approach 1:
The patent divides the physical block into multiple partial physical blocks (e.g., 8 partial blocks of 16 KB each within a 128 KB physical block). This segmentation allows the controller to write data in smaller units (16 KB) that match the host device's write granularity, while still utilizing the larger 128 KB erase unit structure of the flash memory. The address conversion table maps logical addresses to specific partial physical blocks, enabling precise writing without requiring full block erasure.
2Quantity of substance
If the erase unit size is increased to 128 KB, then the memory card capacity is improved, but the write time increases when dealing with 16 KB data units
Solution Approach 1:
By segmenting the 128 KB physical block into 8 partial physical blocks of 16 KB each, the system can write 16 KB data units directly to specific partial blocks without erasing the entire 128 KB block. This maintains the large capacity benefit while reducing write time proportionally to the data size.
Solution Approach 2:
The controller pre-erases specific partial physical blocks before writing data, rather than erasing entire physical blocks. This preliminary action on only the necessary portions (e.g., one 16 KB partial block) significantly reduces the time required compared to erasing full 128 KB blocks, while still achieving the required capacity utilization.
3Speed
If data is written in units of 16 KB matching the host device, then the write speed is improved, but the compatibility with the 128 KB erase unit structure deteriorates
Solution Approach 1:
The patent introduces partial physical blocks as an intermediate layer between the 16 KB host write units and the 128 KB flash erase units. Each physical block is divided into 8 partial blocks, creating a mapping structure that accommodates both granularities. The address conversion table maintains mappings from logical addresses to partial physical block addresses, enabling seamless translation between host requirements and flash memory constraints.
Solution Approach 2:
The partial physical block structure acts as an intermediary layer that mediates between the host device's 16 KB write units and the flash memory's 128 KB erase units. This intermediate structure allows the controller to receive 16 KB writes from the host, map them to appropriate partial physical blocks, and manage them in a way that is compatible with the larger erase unit structure, thus maintaining compatibility while achieving improved write speed.
Data Source
AI summary
It is possible to eliminate the defect that a long time is required for writing into a semiconductor memory card by resulting from the fact, with enlargement of its capacity, that the external data management size is different from the internal data management size in the semiconductor memory card. A partial physical block corresponding to the size managed externally is used regardless of the size of the physical block in a non-volatile memory device. Data are written in the partial physical block unit and an erase block is assured in the physical block unit, thereby enabling the write rate to be increased.