Memory Controller SLC Mapping Backup for Power Loss Recovery
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Solution Overview
Problem
Memory systems face challenges in efficiently recovering physical-logical address mapping information lost due to power loss, as this information is typically stored in volatile DRAM and is not reliably preserved during power outages.
Innovation Solution
The proposed solution involves a memory system architecture that utilizes a combination of single-level cell (SLC) and multi-level cell (MLC) memory blocks, where physical-logical address mapping information is stored in a DRAM and temporarily copied to an SLC memory block, allowing for recovery of this information during power loss by scanning the SLC block.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If physical-logical address mapping information is stored only in volatile DRAM, then the memory system achieves fast access speed, but the information is lost when power loss occurs
Solution Approach 1:
The patent applies preliminary action by copying physical-logical address mapping information from volatile DRAM to non-volatile SLC memory blocks before power loss can occur. The controller continuously maintains copies of mapping information in SLC blocks, ensuring that even if power is lost, the mapping data is already preserved in non-volatile storage and can be recovered without loss.
2Reliability
If physical-logical address mapping information is copied to SLC memory block, then power loss recovery is enabled, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing SLC memory blocks that serve dual functions: they act as regular storage blocks for user data and simultaneously serve as backup storage for physical-logical address mapping information. This multi-functionality reduces the need for separate dedicated backup structures, thereby limiting the increase in device complexity while still providing power loss recovery capability.
3Loss of time
If scanning is performed on SLC memory block for recovery, then power loss recovery time is reduced, but the productivity during normal operation is affected
Solution Approach 1:
The patent applies preliminary action by pre-copying mapping information to SLC blocks during normal operation before power loss occurs. This allows the recovery process to simply read from the already-prepared SLC blocks rather than performing extensive scanning or reconstruction, thereby reducing recovery time without significantly impacting normal operation productivity.
Solution Approach 2:
The patent applies copying by maintaining duplicate copies of physical-logical address mapping information in SLC memory blocks alongside the primary DRAM storage. This copying mechanism enables rapid recovery by simply reading the copied data from SLC blocks after power restoration, minimizing recovery time while allowing normal operations to continue with minimal interruption.
Data Source
AI summary
There are provided a memory system and an operating method thereof. A method for operating a memory system includes: performing a program operation on a first page of a first page group included in a first memory block and storing physical-logical address mapping information on the first page in a physical-logical address mapping information storing section; performing a program operation on a second page of the first page group included in the first memory block and storing physical-logical address mapping information on the second page in the physical-logical address mapping information storing section; and copying the physical-logical address mapping information on the first and second pages of the first page group, which are stored in the physical-logical address mapping information storing section, to a second memory block.