SCSI Driver Path Interchange Retry Control
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Solution Overview
Problem
In computer systems with multiple paths for accessing storage apparatuses, existing technologies face challenges in efficiently changing the number of retries and interchanging paths, particularly when using OS standard SCSI drivers, which can lead to prolonged downtime due to fixed retry settings and difficulty in determining optimal retry values.
Innovation Solution
A data processing apparatus with a processor unit that controls data access by switching paths and determining an upper limit for retries based on path interchange time, allowing for dynamic adjustment of retry counts and path interchanges through user-configurable tables and management systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of retries is increased to improve access reliability, then the reliability of data access is improved, but the time required for path interchange is increased
Solution Approach 1:
The patent applies dynamics by making the retry count configurable and adaptable rather than fixed. The system allows dynamic adjustment of retry counts based on user needs and conditions, enabling the balance between reliability and time to be optimized in different scenarios. The configurable retry count parameter allows the system to adapt its behavior dynamically.
Solution Approach 2:
The patent implements parameter changes by introducing a configurable retry count parameter that can be adjusted by users. This parameter directly controls the number of retry attempts before path interchange, allowing users to modify this parameter to achieve the desired balance between access reliability and path interchange time without changing the system architecture.
2Reliability
If the number of retries is set high to ensure access completion, then the reliability is improved, but the operation complexity increases due to difficulty in determining optimal retry values
Solution Approach 1:
The patent applies self-service by allowing users to independently configure and adjust the retry count parameter according to their specific needs. The system provides the capability for users to manage and optimize their own access parameters without requiring complex system administrator intervention or deep technical knowledge, making the system self-configurable.
Solution Approach 2:
The patent enables dynamic configuration of retry parameters, allowing users to adjust the retry count based on changing conditions and requirements. This dynamic approach replaces static, hard-coded retry values with flexible, user-configurable parameters that can be adapted to different scenarios.
3Reliability
If path interchange is delayed to allow more retries, then the reliability of the current path is maximized, but the productivity decreases due to prolonged downtime
Solution Approach 1:
The patent applies dynamics by enabling flexible control over the retry process through configurable parameters. Users can dynamically adjust the retry count to balance between maximizing path access reliability and minimizing downtime, allowing the system to adapt to different productivity requirements without sacrificing reliability.
Solution Approach 2:
The patent implements parameter changes by introducing a configurable retry count parameter that directly influences the trade-off between reliability and productivity. By modifying this parameter, users can optimize system behavior to achieve the desired balance between maintaining reliable path access and ensuring timely path interchange when necessary.
Data Source
AI summary
In a computer which controls data access with respect to a prescribed logical unit, a processor is configured to: perform, when data access by one path with respect to a logical unit is not completed, control for switching paths with respect to the logical unit; perform communication control in accordance with SCSI with the logical unit by executing a SCSI driver; accept a path interchange time that is a time used as a reference for switching paths with respect to the logical unit; determine an upper limit number of retries in data access by the one path on the basis of the path interchange time; and perform control so that an upper limit number of retries using the one path by the SCSI driver equals the determined number of retries.