Storage Controller Block Release with Uncorrectable Error Handling
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Solution Overview
Problem
During garbage collection in data storage devices, uncorrectable errors in source blocks can prevent them from being released to the free block pool, leading to 'zombie blocks' that remain unusable until a host write occurs, causing host dependency and resource inefficiency.
Innovation Solution
The controller determines the existence of an uncorrectable error in a source block, reads and compares logical addresses from the block's header and the logical-to-physical address table, and copies the affected portion to a destination block, allowing the source block to be released even with uncorrectable errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cluster with uncorrectable error is left in the source block, then data integrity is preserved, but the source block cannot be released to the free block pool causing resource inefficiency
Solution Approach 1:
The patent extracts the problematic cluster with uncorrectable error from the source block and places it in a separate reserved area within the same block. This allows the rest of the block to be released to the free block pool while the erroneous cluster is isolated and preserved, resolving the contradiction between maintaining data integrity and enabling block release efficiency.
2Productivity
If the cluster is copied to destination block despite uncorrectable error, then source block can be released, but corrupted data may be propagated
Solution Approach 1:
The patent converts the harmful effect of uncorrectable errors into a beneficial structure by creating a reserved area within the block that can hold up to 32 clusters with errors. This reserved area acts as a quarantine zone that prevents corrupted data propagation while allowing the block to be fully released, transforming the problem of error handling into a solution that improves both reliability and productivity.
3Reliability
If host write is waited for to release source block, then data safety is maintained, but system responsiveness deteriorates due to host dependency
Solution Approach 1:
The patent performs preliminary action by proactively identifying clusters with uncorrectable errors during the garbage collection process and relocating them to the reserved area before block release. This preliminary error handling eliminates the need to wait for host writes, allowing immediate block release while maintaining data safety, thus improving system responsiveness without sacrificing reliability.
Data Source
AI summary
A data storage device is described that can be configured with various techniques to release a source block to a free block pool even if the source block contains an uncorrectable error in an address header in one of its clusters that would otherwise prevent the release of the source block. The various techniques can be used individually or in combination.