Memory Controller LBA Table Recovery via DRAM List
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Solution Overview
Problem
Existing memory systems face challenges in quickly recovering from sudden power loss, particularly due to the loss of the logical block addressing (LBA) table, which requires time-consuming rebuilding processes and significant write performance degradation.
Innovation Solution
A memory system that includes a list to store block information about super blocks, allowing for efficient rebuilding of the LBA table upon power-up by saving and reading block information from this list, reducing the need to scan every super block and meta page, and accelerating garbage collection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LBA table is rebuilt by scanning every super block and meta page after power loss, then the LBA table can be recovered, but the recovery time becomes excessively long and write performance degrades significantly
Solution Approach 1:
The patent maintains a list in DRAM that stores block information (valid bit and super block number) for each closed super block before power loss occurs. This preliminary action allows the system to quickly recover the LBA table by reading only the necessary block information from the list and a small number of super blocks, rather than scanning all super blocks and meta pages after power loss.
2Reliability
If the LBA table is rebuilt by scanning every super block and meta page after power loss, then the LBA table can be recovered, but write performance degrades significantly
Solution Approach 1:
The list in DRAM is continuously updated with block information for closed super blocks before power loss. This preliminary action eliminates the need for extensive post-power-loss scanning, allowing the system to quickly rebuild the LBA table and resume normal write operations without significant performance degradation.
3Loss of time
If a list storing block information is maintained in DRAM, then recovery time is reduced significantly, but additional memory resources are required
Solution Approach 1:
The patent changes the state of block information from being stored only in non-volatile memory (requiring full scanning) to being maintained in DRAM as a list with valid bits and super block numbers. This parameter change enables faster recovery while the memory overhead is limited to storing metadata for closed super blocks, not all data blocks.
Data Source
AI summary
A memory system may include a memory device including a plurality of a super blocks, a list, and a controller suitable for updating the list with block information regarding one of the super blocks when a super block is opened or closed; and at power up, reading the block information from the list and rebuilding a logical block addressing (LBA) table based on the block information.