Dynamic Wear Balancing in SLC and MLC Memory Regions
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Solution Overview
Problem
The differential wear rates between SLC and MLC regions in rewritable non-volatile memory modules lead to a reduced overall lifetime of memory storage devices, as the SLC region wears faster due to frequent updates and data rebuilding, while the MLC region wears more from random data writes, causing one region to become unusable and shortening the device's lifespan.
Innovation Solution
A memory management method that dynamically selects physical erasing units from either the SLC or MLC regions based on wear values, programming them using the SLC programming mode to balance wear levels, ensuring that frequently accessed data and management tables are stored on less worn units, thereby extending the device's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SLC region is used to record important and frequently-accessed data and management tables, then reading/writing speed and reliability are improved, but the SLC region wears faster due to frequent updates
Solution Approach 1:
The patent implements dynamic wear leveling by continuously monitoring wear values of physical erasing units and adaptively selecting target units for data storage. The system transitions from static region assignment to dynamic unit selection based on real-time wear status, allowing frequently accessed data to be stored on less worn units while balancing the wear distribution across all units over time.
Solution Approach 2:
The patent changes the programming mode parameter dynamically based on wear values. When selecting physical erasing units from the MLC region to store frequently accessed data, the system programs these units using SLC programming mode instead of MLC mode, thereby changing the operational parameters of the same hardware to achieve both speed and wear balancing.
2Quantity of substance
If MLC region is used to record general file data, then storage capacity is increased, but the MLC region wears faster from random data writes
Solution Approach 1:
The system dynamically selects between SLC and MLC physical erasing units based on wear values rather than using fixed region assignments. This allows the MLC region to be utilized more evenly by selecting less worn units for data storage, preventing any single MLC unit from being overused and extending the overall MLC region lifetime while maintaining high storage capacity.
3Reliability
If sufficient space is reserved in advance for SLC region, then frequently-accessed data can be stored reliably, but the MLC region is compressed and overall storage capacity is reduced
Solution Approach 1:
The patent makes physical erasing units universal by allowing units from both SLC and MLC regions to serve as storage targets for frequently accessed data. Instead of reserving specific units exclusively for this purpose, the system can select any unit regardless of its original region designation, making the entire storage capacity available while maintaining reliability through wear-based selection criteria.
Solution Approach 2:
The system dynamically determines which physical erasing units to use for frequently accessed data based on current wear values rather than using fixed reservations. This allows the allocation of storage space to be flexible and adaptive, utilizing available capacity from both SLC and MLC regions while ensuring that reliability requirements are met through selection of appropriate units.
4Reliability
If SLC programming mode is used on MLC physical erasing units, then wear levels are balanced across regions, but programming complexity increases
Solution Approach 1:
The patent changes the programming mode parameter from a static region-based assignment to a dynamic unit-based assignment. The memory control circuit unit monitors wear values and selectively applies SLC programming mode to MLC physical erasing units that are selected as storage targets, rather than applying different modes to entire regions. This parameter change enables wear balancing while managing complexity through selective application.
Data Source
AI summary
A memory management method, a memory storage device and a memory control circuit unit are provided. The method includes: determining whether a relative relation between a first wear value of first physical erasing units initially configured to be programmed based on a first programming mode and a second wear value of second physical erasing units initially configured to be programmed based on a second programming mode is satisfied; and when the relative relation between the first wear value and the second wear value is not satisfied, selecting one or more third physical erasing units from second physical erasing units. The method also includes: programming the one or more third physical erasing units based on the first programming mode to store first data received from a host system into the one or more third physical erasing units.