Memory Error Correction with Chip Kill and Power Saving
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Solution Overview
Problem
Conventional error correction strategies in computer memory systems are inadequate for detecting and correcting errors when less than two full redundant memory chips are available, particularly as memory systems grow larger and require efficient error correction with reduced redundancy.
Innovation Solution
A method and system that access user data from user data chips and system data chips, generating check symbols, computing syndromes, and using discriminator expressions to determine and correct single or double symbol errors, and identify chip failures with minimal redundancy, utilizing Reed-Solomon codes and parallel processing to minimize latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional error correction strategies are used with less than two full redundant memory chips, then memory system reliability deteriorates, but memory system complexity and cost are reduced
Solution Approach 1:
The patent segments the error correction problem into two distinct phases: a learning phase where the system identifies failed memory chips through syndrome analysis, and a recovery phase where the system corrects errors using discriminator expressions. This segmentation allows the system to achieve reliable error correction with less than two full redundant memory chips by treating chip failure identification and error correction as separate, manageable tasks rather than requiring complete redundancy from the outset.
Solution Approach 2:
The patent implements preliminary action by performing syndrome computation and chip failure identification during normal memory operations. The system proactively learns about failed chips and prepares correction mechanisms before actual data corruption occurs. This preliminary identification and preparation of correction expressions enables the system to handle errors efficiently without requiring extensive redundant storage capacity.
2Reliability
If more redundant memory chips are used for error correction, then error detection and correction capability improves, but memory system performance and access speed deteriorate
Solution Approach 1:
The patent employs periodic action by implementing error correction as a two-phase process: during normal operations, the system periodically computes syndromes and identifies failed chips in a learning phase, then transitions to a recovery phase where pre-computed discriminator expressions are used for rapid error correction. This periodic alternation between learning and recovery phases allows the system to maintain high-speed access while periodically enhancing error detection capability without requiring continuous redundant operations.
Solution Approach 2:
The system performs preliminary syndrome analysis and chip failure identification during normal memory operations, preparing correction expressions in advance. When errors occur, the pre-computed discriminator expressions enable rapid correction without requiring extensive real-time computation or additional redundant access cycles, thus maintaining high memory access speed while improving error detection capability.
3Reliability
If full redundant memory chips are allocated for error correction, then chip failure correction reliability improves, but memory capacity and storage efficiency deteriorate
Solution Approach 1:
The patent applies partial action by implementing a learning phase that progressively identifies failed chips and builds correction capability incrementally. The system uses discriminator expressions that are computed based on actual observed failures rather than assuming complete redundancy is needed. This partial approach allows the system to achieve reliable chip failure correction by addressing only the specific failures that occur, rather than allocating full redundant chips for all possible failure scenarios, thereby preserving more usable memory capacity.
Solution Approach 2:
The system dynamically changes parameters by transitioning between learning and recovery phases, adjusting the level of redundancy utilization based on actual failure patterns. During the learning phase, the system adapts to specific chip failures and computes appropriate discriminator expressions. This parameter change allows the system to optimize the balance between correction reliability and usable capacity by tailoring the correction mechanism to actual observed failures rather than using fixed full redundancy.
Data Source
AI summary
A method and system are disclosed for detecting memory chip failure in a computer memory system. The method comprises the steps of accessing user data from a set of user data chips, and testing the user data for errors using data from a set of system data chips. This testing is done by generating a sequence of check symbols from the user data, grouping the user data into a sequence of data symbols, and computing a specified sequence of syndromes. If all the syndromes are zero, the user data has no errors. If one of the syndromes is non-zero, then a set of discriminator expressions are computed, and used to determine whether a single or double symbol error has occurred. In the preferred embodiment, less than two full system data chips are used for testing and correcting the user data.


