Flash Memory Sector Wear-Leveling and Erase Suspension
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Solution Overview
Problem
Non-volatile flash memory is slower than volatile memory, particularly in deletion operations, and is prone to data loss due to limited erasures and aging, with existing solutions not effectively addressing these issues.
Innovation Solution
Implementing a 'wear-leveling' method by writing data to successive sectors, using address pointers to manage sector usage, and suspending erase operations during write or read requests to prevent delays and data loss, while invalidating data to allow for asynchronous sector deletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is written to non-volatile flash memory sectors, then data persistence is achieved, but write operations become slower and data loss risk increases due to erase requirements
Solution Approach 1:
The memory is divided into multiple sectors that can be independently managed. The patent implements a circular buffer mechanism where data is written to the current sector and then rotated to the next sector, allowing continuous writing without waiting for erase operations to complete on all sectors.
Solution Approach 2:
The patent pre-erases sectors before writing to them, ensuring that each sector is in a clean state ready for new data. This preliminary erase action prevents data loss and ensures proper data persistence while maintaining write speed by having ready-to-write sectors available.
2Reliability
If erase operations are performed continuously to maintain data integrity, then data loss is prevented, but memory lifespan decreases due to limited erase cycles
Solution Approach 1:
The patent implements a wear-leveling mechanism that tracks which sectors have been erased the most and rotates the write pointer to use sectors with fewer erase cycles. This distributes the erase workload across all sectors over time, extending the overall memory lifespan while maintaining data integrity through continuous rotation.
Solution Approach 2:
The patent uses a periodic rotation mechanism where data is written to sectors in a cyclic manner, rotating through all sectors in the circular buffer. This periodic writing pattern combined with periodic erasing ensures uniform wear distribution and extends memory lifespan while maintaining data integrity.
3Loss of time
If erase operations are halted during write or read requests, then operational delays are reduced, but erase operations become asynchronous and complex
Solution Approach 1:
The patent implements a dynamic sector management system where the write pointer and erase operations can be adjusted in real-time based on operational needs. The system can halt erase operations during critical write or read requests and resume them later, providing flexible timing that reduces delays while managing complexity through a structured rotation protocol.
Solution Approach 2:
The patent uses feedback mechanisms to track the state of sectors and adjust operations accordingly. The system monitors when sectors are being written to or read from and uses this information to coordinate erase operations, halting them when necessary to avoid conflicts and resuming them when safe, thereby reducing operational delays.
4Productivity
If data is written to successive sectors in a circular buffer, then write speed is improved, but sector management complexity increases
Solution Approach 1:
The patent uses a unified circular buffer structure that serves multiple functions: it manages sequential writing, tracks sector usage, coordinates erase operations, and handles data rotation. This multi-functional approach improves write throughput by eliminating the need for separate management mechanisms while reducing overall system complexity.
Solution Approach 2:
The patent merges the write pointer, erase pointer, and sector tracking logic into a single integrated circular buffer management system. This consolidation allows efficient sequential writing while simplifying the coordination of erase operations, improving throughput without proportionally increasing complexity.
Data Source
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AI summary
The invention describes a method comprising: storing data in a non-volatile flash memory divided into sectors, wherein the data is stored in successive sectors and is written to a new sector each time the data as a whole no longer fits into a previously used sector; wherein, in response to the writing of a new sector, a process reads non-invalidated content from the oldest written sector of the memory, writes it to the next sector, and erases the oldest sector, wherein the erasure process is paused if a write or read request arrives during the erasure process, and wherein the paused erasure process is resumed when the write or read request is completed. A corresponding apparatus is also described.