Memory Controller LBA List Management for Power Loss Data Recovery
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Solution Overview
Problem
Existing memory systems face challenges in ensuring data integrity during unexpected power losses, as the amount of data that can be written to nonvolatile memory using stored capacitor power is limited, potentially leading to data loss when the amount of write-uncompleted data is large.
Innovation Solution
A memory system with a controller that manages a list of logical addresses (LBA list) and storage location information for write-uncompleted data, allowing the controller to write this information to nonvolatile memory using power from a capacitor in case of an unexpected power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power loss protection function writes write-uncompleted data to nonvolatile memory using capacitor power, then data integrity is improved, but the amount of data that can be written is limited to a certain upper limit, causing data loss when the amount of write-uncompleted data is large
Solution Approach 1:
The patent extracts only the essential information (LBA list and storage location information) from the write-uncompleted data and writes this metadata to nonvolatile memory using capacitor power. This allows the system to preserve critical data integrity information without attempting to write all write-uncompleted data, thereby overcoming the limited writing capacity constraint during power loss.
2Reliability
If the system writes all write-uncompleted data to nonvolatile memory during power loss, then data recovery is improved, but the writing time and power consumption increase beyond the limited capacitor power capacity
Solution Approach 1:
The system extracts only the essential metadata (LBA list and storage location information) needed for data recovery and prioritizes writing this information to nonvolatile memory. By omitting the actual write-uncompleted data from the power loss protection writing process, the system stays within the limited capacitor power capacity while still enabling effective data recovery.
Solution Approach 2:
The controller preliminarily manages and organizes the LBA list and storage location information before power loss occurs, so that when power loss happens, the system can immediately write this pre-organized metadata to nonvolatile memory using capacitor power. This preliminary preparation ensures efficient use of the limited power capacity for the most critical recovery information.
3Loss of information
If the system writes LBA list and storage location information to nonvolatile memory during power loss, then identification of lost data is improved, but the writing capacity is still limited by the capacitor power
Solution Approach 1:
The patent extracts only the essential metadata (LBA list and storage location information) from the complete write-uncompleted data set and writes this condensed information to nonvolatile memory. This extraction approach maximizes the use of limited capacitor power for the most critical information needed to identify and recover lost data, while avoiding the futile attempt to write all actual data content.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables clear identification of lost data due to power loss, allowing for effective recovery and minimizing data loss by writing the LBA list and location information to nonvolatile memory within the limited power capacity.
Implementation Method 1
power from a capacitor that stores power to be supplied to the memory system
Data Source
AI summary
According to one embodiment, a controller of a memory system writes, in response to receiving from the host a write command specifying a logical address, data received from the host to a first write destination block. The controller manages a first list and first storage location information, the first list including a plurality of logical addresses corresponding respectively to write-uncompleted data, and the first storage location information indicating a storage location at a beginning of a write-uncompleted region in the first write destination block. In a case where a power loss has occurred without notice from the host, the controller writes the first list and the first storage location information to the nonvolatile memory using power from a capacitor.