Weighted Path Quality Assessment for Storage I/O Error Handling
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Solution Overview
Problem
Conventional storage systems face inefficiencies when handling error events during input/output (I/O) requests, as they often retry requests on the same path that generated the error, leading to delayed processing and resource wastage.
Innovation Solution
A method and system that assess the quality of alternate paths by assigning weights to factors contributing to error repetition, selecting an alternate path if its quality meets a threshold, or choosing the highest quality path if none meet the threshold, to minimize error recurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the storage system retries I/O requests on the same path that generated an error, then the system maintains simplicity in path selection logic, but the processing efficiency deteriorates due to repeated errors and resource wastage
Solution Approach 1:
The system performs preliminary assessment of alternate paths before retrying I/O requests. When an error occurs on a current path, the system proactively evaluates the quality of alternate paths using multiple factors (error history, component status, path characteristics) and selects the best alternate path in advance, preventing repeated failures on the same faulty path
Solution Approach 2:
The system implements feedback mechanisms by monitoring error events on paths and using this information to guide future path selections. The path quality assessment incorporates historical error data and real-time path status, creating a closed-loop system that learns from past errors and adapts path selection decisions accordingly
2Reliability
If the storage system evaluates multiple factors with weights to determine alternate path quality, then the accuracy of path selection improves, but the computational complexity increases
Solution Approach 1:
The system changes parameters by assigning different weights to various path quality factors based on their importance. The weighted scoring mechanism transforms multiple qualitative factors (error history, component status, path characteristics) into a quantitative path quality metric, enabling systematic comparison and selection of the best alternate path
Solution Approach 2:
The path quality assessment is segmented into multiple independent factors, each evaluated separately and then combined through weighting. This segmentation allows the system to independently monitor and adjust the importance of different path characteristics without affecting the entire assessment mechanism
3Reliability
If the system determines path quality based on multiple weighted factors, then the likelihood of selecting a reliable alternate path increases, but the time required for path selection increases
Solution Approach 1:
The system performs preliminary assessments of path qualities and maintains ready-to-use quality metrics for multiple alternate paths. When an error occurs, the system can quickly retrieve pre-evaluated path quality information and select the best path without performing complete re-evaluation, reducing selection time while maintaining reliability
Data Source
AI summary
Method and system for handling error events on a current path for processing an I/O request for reading information from and writing information to a storage space is provided. A system is able to communicate with the storage space via more than one path. If the current path reports an error event, then an alternate path quality is determined to ascertain whether the alternate path will generate an error similar to the current path. The alternate path quality is determined based on a plurality of factors which are assigned certain weights. The weights are determined based on a likely contribution of each factor to a repetition of the error reported by the current path. If the alternate path quality is equal to or exceeds a programmable threshold value, then the alternate path is selected.