Flash Memory Cache Backup Method for Timeout Prevention
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Solution Overview
Problem
Flash memory storage devices experience significant delays when writing large amounts of data from cache memory to physical units, particularly when multiple logical units are involved, leading to operational inefficiencies and potential data loss due to sudden disconnections.
Innovation Solution
A data backup method and flash memory controller that quickly copy data from cache memory to a cache area upon receiving a trigger signal, using a microprocessor unit, flash memory interface, host interface, and memory management unit to map logical addresses to data or cache areas, ensuring continuous writing into adjacent physical addresses and maintaining data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data is temporarily stored in cache memory to enhance writing efficiency, then writing speed is improved, but data loss risk increases due to sudden disconnections
Solution Approach 1:
The patent applies preliminary action by copying data from cache memory to a backup area in the flash memory before actual writing occurs. When a flush command is received, the system proactively creates a backup copy of cache data to the backup area, ensuring data safety before any potential disconnection can occur. This advance preparation resolves the contradiction by maintaining both fast cache-based writing and reliable data protection.
2Loss of time
If cache memory is used to shorten command completion time, then operational efficiency is improved, but system delay increases when flushing large amounts of data
Solution Approach 1:
The patent segments the data writing process into two independent paths: a fast path where data is quickly copied from cache to the backup area in flash memory, and a separate path for eventual data migration from backup area to data area. This segmentation allows the flush command to complete rapidly by only requiring the cache-to-backup copy operation, while the slower backup-to-data area migration occurs independently, thus resolving the time contradiction.
Solution Approach 2:
The backup area serves as an intermediary storage layer between cache memory and the data area. Instead of directly transferring large amounts of data from cache to data area (which causes delays), the system uses the backup area as a intermediate staging ground. This intermediary approach enables rapid flush operations while maintaining the eventual integrity of data storage.
3Reliability
If physical units are alternated for data writing, then data integrity is improved, but operation time increases due to mapping updates
Solution Approach 1:
The patent applies preliminary action by pre-copying cache data to the backup area before the actual data area writing occurs. This preliminary copy ensures data integrity is preserved in a safe location immediately, while the mapping table updates and data area writing can proceed in the background without blocking the flush command completion, thus resolving the time-integrity contradiction.
Data Source
AI summary
A data backup method for backing up data temporarily stored in a cache memory of a flash memory storage device is provided, where the flash memory storage device has a plurality of physical units. The data backup method includes logically grouping a portion of the physical units into a data area and a cache area. The data backup method also includes determining whether a trigger signal is received; and when the trigger signal is received, copying the data temporarily stored in the cache memory into the cache area. Accordingly, the data backup method can quickly write the data temporarily stored in the cache memory into the physical units, thereby preventing a time out problem which may occur in the flash memory storage device.