Alias Management Group for Cross-Subsystem I/O Address Sharing

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Solution Overview

Problem

In computing environments, hosts are limited to using alias addresses within the same logical subsystem as the base address for directing I/O requests to logical volumes, which restricts the availability and utilization of alias addresses across different logical subsystems.

Innovation Solution

The implementation of an alias management group that allows any alias address on one logical subsystem to be used to issue an I/O request to any base address on another logical subsystem within the same management group, enabling the sharing and pooling of alias addresses across multiple logical subsystems.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If alias addresses are confined to the same logical subsystem as the base address, then the system maintains simple address management and clear address scope, but the availability and utilization of alias addresses are restricted across different logical subsystems

Engineering Contradiction:

Improveavailability of alias addressesVSAvoidaddress management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements an alias management group that allows alias addresses to be shared across multiple logical subsystems. Instead of confining each alias address to a single logical subsystem, the system creates a pooled resource where alias addresses can be dynamically allocated to any logical device within the management group, enabling one alias address to serve multiple bases across different subsystems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges multiple logical subsystems into a unified alias management group. By combining the address spaces and alias pools of individual logical subsystems into a shared resource pool, the system enables cross-subsystem alias addressing while maintaining centralized management through the channel subsystem's path selection capabilities.

Inventive Principle:

Principle #5Merging (Combining)

2Productivity

If multiple alias addresses are allocated to each logical volume to accommodate concurrent I/O requests, then the system can handle more concurrent operations, but the shortage of alias addresses occurs when the number of logical volumes increases

Engineering Contradiction:

Improveconcurrent I/O operationsVSAvoidnumber of available alias addresses

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent implements dynamic alias address allocation where the binding between alias addresses and logical devices is not fixed but can change based on current system state. The channel subsystem dynamically selects which alias address to use for each I/O request based on available resources and current workload, allowing alias addresses to be reassigned between different logical devices as needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent enables alias addresses to be released back to the pooled resource when no longer needed by a particular logical device. When a logical volume completes its I/O operations or releases its alias addresses, those addresses are recovered into the shared pool and can be reallocated to other logical devices that need them, thus reducing the total number of alias addresses required in the system.

Inventive Principle:

Principle #34Discarding and recovering

3Reliability

If alias addresses are statically assigned to specific base addresses, then the system provides predictable address mapping, but the flexibility to share alias addresses across different logical devices is limited

Engineering Contradiction:

Improveaddress mapping predictabilityVSAvoidalias sharing capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent segments the alias address management into two layers: a static configuration layer that defines the alias management group membership and resource pool boundaries, and a dynamic operation layer that handles runtime alias allocation and selection. This segmentation allows the system to maintain predictable group boundaries while enabling flexible address mapping within those boundaries.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces the channel subsystem as an intermediary between alias addresses and logical devices. Rather than direct static mapping, the channel subsystem acts as a mediator that receives I/O requests, selects appropriate alias addresses from the pooled resources, and routes them to the correct logical devices based on current system state and available resources.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10983708B2Sharing alias addresses among logical devices

Publication Date: 2021.04.20 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Provided are a computer program product, system, and method for sharing alias addresses among logical devices by a host accessing logical devices provisioned with a capacity from physical devices managed by a control unit. The host establishes with the control unit an association of logical devices and alias addresses assigned to the logical devices, wherein the alias addresses are associated with an alias management group. Alias address pool information is generated indicating each of the logical devices and their assigned alias addresses indicated in the association. The host uses from the alias address pool information any one of the alias addresses in the alias address pool information to access any of the logical devices associated with the same alias management group as the alias address.