Memory System Roll-Forward Recovery After Abnormal Power-Off
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Solution Overview
Problem
Non-volatile storage devices like SSDs face data inconsistency and corruption issues during abnormal power-off events due to incomplete data synchronization, particularly in systems using Flash-Friendly File System (F2FS), leading to undesirable data loss and user experience degradation.
Innovation Solution
Incorporating direct node address information into the protection information (PI) field of data blocks, allowing for a roll-forward recovery process to verify and recover only valid data blocks post-power-up, ensuring data consistency by comparing node address information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data synchronization is performed during normal operation, then data consistency is maintained, but data corruption occurs during abnormal power-off due to incomplete synchronization
Solution Approach 1:
The patent stores node address information in advance within the PI field of each data block before writing occurs. This preliminary embedding of verification data enables the system to validate data integrity during recovery operations without requiring complete resynchronization, thus preventing corruption while maintaining consistency.
Solution Approach 2:
The patent implements a feedback mechanism where node address information is retrieved and verified during power-up recovery. This feedback loop allows the system to detect and discard corrupted data blocks that fail verification, while accepting valid blocks, thereby maintaining data consistency after abnormal power-off events.
2Productivity
If all data blocks are recovered after power-up, then data availability is improved, but data integrity deteriorates due to inclusion of corrupted blocks
Solution Approach 1:
The patent applies different quality standards to different data blocks during recovery. Each data block is individually verified using its embedded node address information from the PI field. This local quality control allows selective acceptance or rejection of blocks based on their specific verification results, ensuring both availability and integrity.
Solution Approach 2:
The patent changes the verification parameter during recovery operations by comparing node address information embedded in the PI field against expected values. This parameter-based verification approach enables dynamic determination of data block validity, allowing the system to recover available data while filtering out corrupted blocks.
3Reliability
If node address verification is performed for each data block, then data integrity is ensured, but processing time increases during recovery
Solution Approach 1:
The patent performs partial verification action by checking only the node address information embedded in the PI field of each data block during recovery, rather than performing complete data validation. This partial action approach maintains data integrity through targeted verification while significantly reducing recovery time compared to exhaustive checking methods.
Data Source
AI summary
In certain aspects, a host is disclosed. The host includes a memory configured to store instructions and a processor coupled to the memory. Responsive to execution of the instructions, the processor is configured to determine a power-up event after abnormal power-off and perform a roll-forward recovery for a memory system. A set of node blocks to be recovered is determined. For each node block included in the set of node blocks, a first data block stored in the memory system is determined based on the node block. It is determined whether first node address information retrieved from a metadata part of the first data block matches second node address information of the node block. It is determined whether to recover the node block and the first data block in the memory system based on whether the first node address information matches the second node address information.