Nonvolatile Memory Controller Sequential Write Management
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Solution Overview
Problem
Conventional recordable memory devices face challenges in maintaining real-time recording performance due to data fragmentation and write errors, which lead to reduced memory performance and potential data loss during retry operations.
Innovation Solution
A recordable memory device with a controller that manages data writing from the next physical address after the final recorded data, using a nonvolatile semiconductor memory with a system area for address conversion, eliminating the need for an address conversion table in the user area and enabling continuous data transfer without temporary stoppages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If data is managed using a file allocation table (FAT) file system, then data can be organized and accessed, but data fragmentation occurs during write or erase operations, reducing memory performance
Solution Approach 1:
The patent extracts the address conversion function from the user-area FAT file system and relocates it to the system area managed by the controller. This separation allows the user area to maintain simple sequential addressing while the controller handles address conversion, preventing fragmentation and maintaining high write performance.
2Productivity
If write operations are performed on fragmented NAND blocks, then data can be recorded, but overhead of write time occurs and memory performance is reduced
Solution Approach 1:
The controller performs preliminary address conversion and data relocation operations before the host initiates write operations. By pre-organizing data in the system area with proper address mapping, the controller eliminates the need for time-consuming fragmentation handling during actual write operations, reducing write time overhead.
3Reliability
If error notification is given to the host apparatus during real-time recording, then errors can be detected, but data transfer is temporarily stopped and data may be lost
Solution Approach 1:
The controller acts as an intermediary between the NAND flash memory and the host apparatus, absorbing and handling errors internally without notifying the host. This allows the controller to manage retries and error correction in the background while maintaining continuous data transfer, ensuring both error detection and real-time recording continuity.
4Adaptability or versatility
If an address conversion table is maintained in the user area, then address mapping can be performed, but chip cost increases
Solution Approach 1:
The controller is designed with universal address conversion capabilities that serve multiple functions: managing system area operations, handling user area access, performing address mapping, and managing error recovery. This multi-functionality eliminates the need for a separate address conversion table in the user area, reducing chip cost while maintaining full address mapping capability.
Data Source
AI summary
A recordable memory device includes a nonvolatile semiconductor memory, and a controller controlling the nonvolatile semiconductor memory based on a recordable system. The nonvolatile semiconductor memory has a user area capable of directly making an access from a host, and a system area managed by the controller. A data writing to the reformatted user area of the nonvolatile semiconductor memory executes from a start point which is an unused area after the final physical address of old recordable data recorded in the user area before the reformat. The data writing executes from a start point which is a top physical address in the user area, when the start point exceeds the final physical address in the user area.