Multipath Storage Path Verification Method
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Solution Overview
Problem
Existing multipath storage systems face challenges in verifying the successful switching to alternate paths during hardware failures or service disruptions, which can lead to unsatisfactory operation of the alternating paths, especially when devices or connections are down or disabled without proper alerting.
Innovation Solution
A method is introduced to identify primary and secondary storage control ports for specific LBA ranges, reduce outbound I/O operations at the primary port to simulate switching to an alternate path, analyze responsive changes at the secondary port, and verify operability based on predefined criteria, ensuring seamless switching and continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple paths are configured in a storage system to enable failover and load balancing, then system reliability and availability are improved, but the complexity of path verification and failure detection increases
Solution Approach 1:
The patent applies preliminary action by establishing alternate paths and their operational status in advance before actual failures occur. The system pre-configures multiple paths (primary and alternate) and maintains awareness of their states through continuous monitoring, enabling rapid failover when needed without requiring complex real-time verification during failure events.
Solution Approach 2:
The patent implements feedback mechanisms through continuous monitoring of path operational status, I/O operation states, and device health conditions. This feedback loop enables the system to detect failures, determine path availability, and switch between paths automatically, reducing the complexity of manual verification while maintaining high reliability.
2Measurement precision
If the system continuously monitors path status and I/O operations to verify switching operability, then path failure detection accuracy is improved, but system overhead and processing resources increase
Solution Approach 1:
The patent applies periodic action by implementing continuous monitoring at specific intervals rather than constant real-time analysis. The system periodically checks path operational status, device states, and I/O operation conditions, which provides sufficient detection accuracy while reducing processing resource consumption compared to continuous real-time monitoring.
Solution Approach 2:
The patent implements self-service by having the storage system automatically monitor its own path status, detect failures, and perform failover without requiring external intervention. The system uses its own resources to track operational states and make decisions, reducing the need for additional dedicated monitoring infrastructure and processing resources.
3Reliability
If the system reduces outbound I/O operations at the primary port to simulate switching scenarios, then verification of alternate path operability is improved, but I/O operation interruptions increase
Solution Approach 1:
The patent applies partial action by selectively reducing outbound I/O operations at the primary port only during verification scenarios rather than continuously. The system maintains normal I/O operations during regular operation and only implements reduced outbound operations when alternate path verification is required, minimizing I/O interruptions while enabling reliable path verification.
Solution Approach 2:
The patent uses preliminary action by performing alternate path verification during maintenance windows or low-activity periods rather than during active I/O operations. The system prepares verification scenarios in advance and executes them when appropriate, ensuring that path operability is verified without causing significant I/O interruptions during normal operation.
Data Source
AI summary
There is provided a method of operating a multipath storage system, the method comprises: identifying a primary storage control port configured to be responsible for a given LBA range and a secondary storage control port configured to have secondary responsibility for the given LBA range; reducing, in a manner unaffecting respective inbound I/O operation, outbound I/O operation related to the given LBA range and occurring at the primary storage control port, thereby causing a situation requiring switching all respective I/O requests to an alternating path; analyzing responsive changes in outbound I/O operation related to the given LBA range and occurring at the secondary storage control port, and verifying operability of switching to the alternating path in accordance with the obtained results. Outbound I/O operation can be reduced with the help of a routine configured to identify inbound I/O requests directed to the given LBA range and to put these requests on hold for a delay period, thus giving rise to delayed I/O requests, wherein the delay period is configured to be long enough to enable switching to an alternating path.