ALUA Path Selection Engine Using Hop Count Metrics
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Solution Overview
Problem
Conventional techniques for selecting active-optimized paths in Asymmetric Logical Unit Access (ALUA) systems do not consider the number of 'hops' between host devices and storage subsystems, leading to inefficient data exchanges due to the selection of paths that require more hops than necessary.
Innovation Solution
An Information Handling System (IHS) with a path selection engine that receives and transmits hop counts between host devices and storage subsystems, allowing the host device to select an active-optimized path with the fewest number of hops by retrieving and utilizing hop count information from communications generated by host devices and storage subsystems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional path selection techniques are used in ALUA systems, then paths can be selected between host devices and storage subsystems, but the number of hops is not considered resulting in inefficient data exchanges
Solution Approach 1:
The patent changes the selection criterion from conventional path selection to hop count-based selection. The path selection engine retrieves hop count values from FDISC communications and uses this parameter to determine the optimal path, thereby improving data exchange efficiency by minimizing the number of hops between host devices and storage subsystems
Solution Approach 2:
The patent implements feedback by having the path selection engine continuously monitor and retrieve hop count information from FDISC communications generated during fabric login procedures. This feedback mechanism allows the system to adapt path selections based on current network conditions and hop count measurements, ensuring optimal data exchange paths are selected
2Reliability
If active-optimized paths are selected without considering hop count, then storage controllers can be directly accessed, but more hops are required compared to active-non-optimized paths
Solution Approach 1:
The patent introduces hop count as a new selection parameter that supersedes conventional path selection criteria. By retrieving and comparing hop count values from different paths, the system can accurately identify the optimal path that minimizes hops while maintaining reliable access to storage controllers, thereby resolving the contradiction between path selection accuracy and data exchange efficiency
Data Source
AI summary
An ALUA path selection system includes a networking device in a networking fabric that couples a host device to a storage subsystem. The networking device receives a host device communication generated by the host device and retrieves a host device hop count that identifies a number of hops between the host device and the networking device. The networking device also receives a storage subsystem communication generated by the storage subsystem and retrieves a storage subsystem hop count that identifies a number of hops between the storage subsystem and the networking device. When the networking device receives a hop count request from the host device, it transmits the host device hop count and/or the storage subsystem hop count to the host device, and the host device uses the host device hop count and/or the storage subsystem hop count to select an active-optimized path to a LUN included in the storage subsystem.