SSD Controller Bad Memory Unit Detection at Die and Plane Granularity
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Solution Overview
Problem
Solid-state drives (SSDs) face significant capacity loss and performance degradation due to memory die or plane failures, which are not effectively detected and handled by existing technologies, leading to potential data loss and reduced over-provisioning, especially in enterprise applications.
Innovation Solution
Implementing a method for dedicated bad memory unit detection at the die and plane granularity within the SSD controller, allowing for real-time and manufacturing-time detection, proactive measures, and integration with firmware to manage and recover data, avoiding reliance on bad block detection alone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bad block detection and handling is used, then individual block failures can be managed, but the time to detect and handle bad blocks in a failed die/plane becomes very long
Solution Approach 1:
The patent performs preliminary testing of memory blocks during manufacturing to identify and mark bad blocks before they cause failures during operation. This preliminary detection action allows the system to prepare handling procedures in advance, reducing the time needed to respond when actual failures occur during SSD operation.
2Device complexity
If no dedicated die failure detection algorithm is implemented, then the system remains simpler, but capacity loss and functionality loss increase significantly
Solution Approach 1:
The patent segments the memory detection process into multiple levels: block-level testing during manufacturing, plane-level monitoring during operation, and die-level failure detection. This segmentation allows dedicated algorithms to be applied at appropriate levels without overwhelming complexity, while effectively detecting and containing failures to minimize capacity loss.
3Quantity of substance
If memory density increases, then storage capacity improves, but the potential loss of capacity due to die/plane failure increases
Solution Approach 1:
The patent implements feedback mechanisms where the controller continuously monitors memory block status and provides information back to the system about failed blocks and planes. This feedback enables the system to adjust its operation dynamically, isolating failed areas and preserving usable capacity even as memory density increases, thereby maintaining reliability despite higher potential loss scenarios.
Data Source
AI summary
An apparatus comprising a memory and a controller. The memory is configured to process a plurality of read/write operations. The memory comprises a plurality of memory unit granularities each having a size less than a total size of the memory. The controller is configured to process a plurality of I/O requests to the memory units of the memory that are not marked as bad on a memory unit list. The controller is configured to track a plurality of bad blocks of the memory. The controller is configured to determine which of the memory units to mark as bad based on a test of whether a unit of memory larger than a block of the memory has failed. The test is based on a threshold of the bad blocks in the unit of memory.