SSD Controller Emergency Data Recovery Mechanism
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Solution Overview
Problem
In solid state drives (SSDs), sudden power disconnections can lead to incomplete writing of data, causing errors in error-correction decoding due to the need for increased backup battery capacity, which increases costs and reduces performance.
Innovation Solution
The memory system saves not-yet written data and storage location information in an emergency save area during power disconnection, allowing for error correction upon power return by using dummy values to complete the writing process, thereby reducing the need for increased backup battery capacity and improving error-correction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If backup battery capacity is increased to maintain data during power disconnection, then data reliability is improved, but production cost increases
Solution Approach 1:
The patent performs preliminary actions by detecting power disconnection before it occurs and proactively saving incomplete write data to a designated area in the nonvolatile memory. This advance preparation eliminates the need for large backup battery capacity, as the system already has the data ready when power is restored.
Solution Approach 2:
The patent introduces an intermediary mechanism - a designated area in nonvolatile memory that serves as a temporary storage location for incomplete write data during power disconnection. This intermediary storage allows the system to maintain data reliability without requiring increased backup battery capacity.
2Measurement precision
If backup battery capacity is increased to maintain data during power disconnection, then error-correction accuracy is improved, but production cost increases
Solution Approach 1:
The system performs preliminary detection of power disconnection and saves incomplete data before power is lost. This ensures that when power returns, the error correction process has complete and accurate data to work with, maintaining high error-correction accuracy without needing larger backup batteries.
Solution Approach 2:
The designated nonvolatile memory area acts as an intermediary that preserves incomplete write data during power disconnection. This intermediary storage ensures data integrity is maintained, allowing accurate error correction upon power return without requiring increased backup battery capacity.
3Measurement precision
If data is saved in emergency save area during power disconnection, then data reconstruction accuracy is improved, but device complexity increases
Solution Approach 1:
The patent makes the nonvolatile memory serve multiple functions - it acts as both the primary storage for normal operations and as an emergency save area during power disconnection. This multi-functionality improves data reconstruction accuracy without adding separate dedicated hardware components, thus avoiding increased device complexity.
Solution Approach 2:
The system uses its own nonvolatile memory resources to save incomplete data during power disconnection, rather than requiring external backup systems. This self-service approach improves data reconstruction accuracy while avoiding the complexity of additional external components.
Data Source
AI summary
According to one embodiment, in a memory system, a controller is configured to write a first data among write data to be written across the multiple chips of the first memory area into part of the first memory area and write, in response to a power supply disconnection being detected before writing a second data among the write data into the first memory area, a first information about a storage location where the second data has been stored and the second data into the second memory area. The controller is configured to read, in response to power return being detected, the first data from the part of the first memory area, and read the first information from the second memory area. The controller is configured to generate a second information about a reference location to access the second data based on the read first information.