Memory Controller Wear-Leveling and Failure Remapping
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Solution Overview
Problem
Combining start-gap wear-leveling and FREE-p failure remapping techniques in computing systems results in undesirable outcomes, such as further damage to failed memory locations due to additional writes, as the existing methods do not ensure compatibility and proper handling of remapped memory locations.
Innovation Solution
A memory controller is configured to detect failed memory locations, remap them to spare locations outside the wear-level region, and maintain the FREE-p pointer, while also implementing a strategy to copy data from a new gap location to the previous gap location, keeping the pointer in the failed location and moving data from another location to the spare location referenced by the pointer, thus avoiding writes to the failed location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If start-gap wear-leveling is implemented to rotate physical addresses, then memory wear is distributed evenly, but failed memory locations may be overwritten with additional writes causing further damage
Solution Approach 1:
The system performs preliminary detection of failed memory locations and establishes remapping pointers before wear-leveling operations proceed. By pre-identifying failed locations and setting up remapping infrastructure, the system prevents subsequent wear-leveling writes from damaging these vulnerable locations further.
Solution Approach 2:
The patent introduces an intermediary remapping mechanism that sits between the wear-leveling algorithm and the physical memory locations. When wear-leveling needs to write to a failed location, the remapping pointer redirects the write operation to a spare location, thus protecting the failed location from additional writes while maintaining wear-leveling functionality.
2Reliability
If FREE-p failure remapping is used to redirect failed memory locations to spare locations, then data access is maintained, but compatibility with wear-leveling algorithms is lost resulting in improper handling of remapped locations
Solution Approach 1:
The patent creates a universal interface that allows both wear-leveling algorithms and failure remapping to operate together. The remapping pointer structure is designed to be transparent to the wear-leveling algorithm, allowing it to function normally while the remapping layer handles failed locations. This multi-functional design enables both wear distribution and failure recovery to coexist.
Solution Approach 2:
The system implements feedback mechanisms where the memory controller continuously monitors memory location status and dynamically adjusts remapping pointers. When wear-leveling operations are performed, the system receives feedback about which locations are being accessed and updates remapping accordingly to prevent writes to failed locations while maintaining compatibility with the wear-leveling pattern.
Data Source
AI summary
In one example a system includes a memory, and at least one memory controller to: detect a failed first memory location of the memory, remap the failed first location of the memory to a spare second location of the memory based on a pointer stored at the failed first memory location, and wear-level the memory. To wear-level the memory, the memory controller may copy data from the spare second location of the memory to a third location of the memory, and keep the pointer in the failed first memory location.