SSD Block Format Conversion for Extended Write-Erase Cycles
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Solution Overview
Problem
Solid state disks (SSDs) face premature failure due to bad blocks formed from excessive write/erase cycles, leading to inefficient usage and waste, as current management mechanisms do not allow reuse of blocks before they become defective.
Innovation Solution
Implement a method where the SSD monitors write/erase times of physical blocks and converts them from multi-level or three-level storage formats to single-level formats when the write/erase count exceeds a predetermined limit, effectively extending the SSD's lifetime by reusing potentially defective blocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SSD uses current bad block management mechanism that never reuses bad blocks, then the reliability is maintained by avoiding defective blocks, but the productivity decreases due to wasted blocks and reduced usable capacity
Solution Approach 1:
The patent changes the parameter of storage format from multi-level (MLC/TLC) to single-level (SLC) for blocks that have reached their write/erase limit. This parameter change allows the block to be reused with extended lifetime while maintaining data integrity, thus resolving the contradiction between reliability and productivity by enabling continued use of blocks that would otherwise be discarded
2Duration of action of stationary object
If the SSD converts physical blocks from multi-level storage format to single-level storage format when write/erase times exceed the upper limit, then the duration of action is extended by reusing blocks, but the device complexity increases due to format conversion management
Solution Approach 1:
The patent segments the flash memory into multiple physical blocks and implements differential management strategies for each block based on their write/erase cycle counts. Some blocks remain in multi-level format while others are converted to single-level format, allowing the system to extend overall SSD lifetime through selective format conversion without requiring complete system redesign
Solution Approach 2:
The controller acts as an intermediary that manages the format conversion process between multi-level and single-level storage formats. It monitors write/erase times, determines when conversion is needed, and executes the conversion automatically, thereby extending SSD lifetime while abstracting the complexity from the user and managing the transition smoothly
Data Source
AI summary
The present disclosure illustrates a method of extending a lifetime of a solid state disk (SSD). The SSD includes a flash memory which is a multi-level cell (MLC) flash memory. The method includes steps of: setting a number of logic blocks of the SSD to be one-half of a number of physical blocks of the flash memory; reading, by a control unit of the SSD, a write/erase times of each of the physical blocks of the flash memory; and converting the physical block, of which a number of the write/erase times exceeds an upper limit of the write/erase times, from a multi-level storage format to a single-level storage format. A number of the logic blocks is a constant value.