Simulated I/O Subsystem for Mainframe Fault Injection

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Solution Overview

Problem

Current methods for testing and evaluating the fault tolerance of mainframe computer systems, such as IBM's System z, are costly and limited in simulating realistic fault conditions, particularly for I/O operations, due to the complexity and cost of running actual mainframe environments.

Innovation Solution

A simulated computing environment is created, including a simulated z/OS operating system and System z platform with a modifiable I/O subsystem, using a fault injector to inject I/O faults and emulate FICON communication, allowing for cost-effective evaluation of fault tolerance and compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If actual mainframe hardware and software are used for testing, then fault tolerance evaluation is accurate, but cost and complexity increase significantly

Engineering Contradiction:

Improvefault tolerance evaluation accuracyVSAvoidtesting environment complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates a simulated computing environment that copies the essential characteristics of a mainframe system without requiring actual mainframe hardware. The simulation includes a virtualized I/O subsystem that replicates mainframe I/O behavior, allowing fault injection and tolerance testing while reducing complexity and cost.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent introduces a fault injector as an intermediary component that can inject faults into the simulated I/O subsystem. This mediator enables controlled fault injection without requiring direct manipulation of the mainframe system, facilitating safe and accurate fault tolerance evaluation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If actual mainframe hardware is used for testing, then I/O fault simulation is realistic, but cost increases significantly

Engineering Contradiction:

ImproveI/O fault simulation realismVSAvoidtesting cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent uses software-based simulation to copy mainframe I/O subsystem behavior rather than using physical hardware. The simulated I/O subsystem maintains realistic fault characteristics while dramatically reducing the cost of setting up and maintaining the testing environment.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces physical mainframe hardware with software-based simulation mechanisms. The I/O subsystem is emulated through software layers that replicate mainframe I/O behavior, substituting expensive hardware with more cost-effective software implementation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If simulated computing environment is used, then cost is reduced, but fault injection capability is limited

Engineering Contradiction:

Improvetesting costVSAvoidfault injection capability

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements a dynamic fault injection mechanism that can adaptively introduce various types of faults into the simulated I/O subsystem. The fault injector can modify simulation parameters and inject different fault conditions based on testing requirements, maintaining versatility despite using a simplified simulated environment.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9170904B1I/O fault injection using simulated computing environments

Publication Date: 2015.10.27 EMC IP HLDG CO LLC

AI summary

A system for injecting I/O faults into a closed system, for example, the injection of link level I/O faults, involves the use of a simulated computing environment. In an embodiment, the system provides for fault injection using an emulated IBM System z environment and including the use of FICON and/or other suitable communication channel protocols. The emulated System z environment may include a simulated z/OS and/or emulated System z hardware and software components.