Host Multi-Path Layer Automatic Storage Local-Remote Detection
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Solution Overview
Problem
Storage systems in information processing systems often face inefficiencies due to unawareness of storage-side local-remote designations, leading to suboptimal path selection and performance issues, especially in configurations where different paths have varying performance characteristics.
Innovation Solution
A multi-path layer in host devices automatically detects storage-side local-remote designations by obtaining asymmetric access state information, such as ALUA or ANA state information, and adjusts path selection to favor paths to the designated local storage system over the remote one, using MPIO drivers to send and process commands for this purpose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the host device uses default path selection without awareness of storage-side local-remote designations, then the system configuration is simple and easy to implement, but the path selection performance is suboptimal and IO operations may be routed through slower remote paths instead of faster local paths
Solution Approach 1:
The host device obtains asymmetric access state information from the storage system and uses this feedback to dynamically adjust path selection. The multi-path layer receives ALUA/ANA state information indicating whether each path is optimized or non-optimized, and uses this information to preferentially select optimized paths for IO operations, thereby resolving the contradiction between simple default path selection and performance-optimized path selection.
Solution Approach 2:
The host device automatically detects and determines local-remote designations of storage systems without requiring manual configuration or external intervention. The multi-path layer autonomously obtains asymmetric access state information, determines which storage system is local versus remote, and adjusts path selection accordingly, enabling the system to self-optimize performance without increasing operational complexity.
2Productivity
If the host device automatically detects storage-side local-remote designations and adjusts path selection, then path selection performance is optimized, but the multi-path layer complexity increases due to additional detection and determination mechanisms
Solution Approach 1:
The patent uses asymmetric access state information (ALUA/ANA) as an intermediary mechanism that bridges the host device and storage system. This intermediary provides the necessary local-remote designation information without requiring complex direct communication or configuration protocols between the host and storage systems, thereby optimizing path selection while limiting the increase in multi-path layer complexity.
3Measurement precision
If the host device obtains asymmetric access state information from the storage system, then accurate local-remote designation detection is achieved, but additional communication overhead and processing time are required
Solution Approach 1:
The host device obtains asymmetric access state information as part of the initial path discovery and setup process, before actual IO operations begin. By performing this detection preliminarily, the system establishes accurate local-remote designations in advance, avoiding the need for repeated detection during runtime and minimizing the time impact on actual data operations.
Data Source
AI summary
An apparatus in one embodiment includes at least one processing device comprising a processor coupled to a memory. The at least one processing device is configured to obtain in a host device asymmetric access state information for one or more logical storage devices each accessible in at least first and second storage systems, and to determine, based at least in part on the asymmetric access state information obtained for the one or more logical storage devices, local-remote designations of respective ones of the first and second storage systems. The asymmetric access state information for a given one of the logical storage devices illustratively comprises, for each of two or more storage controllers of each of the first and second storage systems, information indicating whether a corresponding set of paths is in an active-optimized (AO) state or an active-non-optimized (ANO) state.