MPIO Logical Volume Backed Virtual Disks via Redundant VIOS

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Solution Overview

Problem

Current techniques fail to enable multipath input/output (MPIO) for logical volume backed storage devices through redundant virtual I/O servers (VIOSs due to data inconsistency issues when multiple VIOSs access the same logical volume.

Innovation Solution

The method involves creating a logical volume on a first VIOS, activating it in a specific access mode, importing it to a second VIOS with a different access mode, and mapping it as a backing storage device, while configuring multiple paths to prevent simultaneous access and switch to redundant paths in case of failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple VIOSs access the same logical volume simultaneously, then redundancy and high availability are improved, but data inconsistency issues occur

Engineering Contradiction:

Improvehigh availabilityVSAvoiddata consistency

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces a client device as an intermediary that coordinates access to the logical volume through multiple VIOSs. The client device receives I/O requests, determines the active VIOS, and routes requests through the appropriate path, preventing simultaneous access that would cause data inconsistency while maintaining redundancy for high availability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary actions by establishing active and passive paths before I/O operations occur. The client device pre-determines which VIOS is active and configures the access paths accordingly, so that when I/O requests arrive, the routing decision has already been made, preventing data inconsistency while maintaining failover capability

Inventive Principle:

Principle #10Preliminary action

2Reliability

If MPIO is enabled through redundant VIOSs, then fault tolerance is improved, but system complexity increases

Engineering Contradiction:

Improvefault toleranceVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The client device performs self-service by automatically determining the active VIOS and routing I/O requests without requiring complex external coordination. The system self-manages the active-passive path switching and failover logic, reducing the need for additional complexity in the VIOS architecture itself

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS10921993B2Supporting MPIO for logical volume backed virtual disks

Publication Date: 2021.02.16 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Embodiments include systems, methods, and computer program products to perform an operation for enabling multipath I/O for logical volume backed virtual disks through redundant virtual I/O servers (VIOSs) on a computing system. The operation generally includes creating, from a physical storage device, a logical volume on a first VIOS. The logical volume on the first VIOS is activated in a first access mode. The operation also includes importing the logical volume to a second VIOS. The logical volume on the second VIOS is activated in a second access mode different from the first access mode. The operation further includes mapping the logical volume on the first and second VIOSs as a backing storage device for at least one logical partition hosted on the computing system.