Task: Optimize Dependability Architecture
This task is about run-time risk management through the identification and specification of control measures focusing on safety, reliability, and security.
Purpose
The purpose of the this task to specify large scale structures, behaviors and optimizations specific to the dependability of the system - especially safety, reliability, and security.
Relationships
RolesPrimary: Additional: Assisting:
InputsMandatory: Optional: External:
  • None
Outputs
Main Description

Dependabilty is managed through the structuring of the system to provide data and control redundance to detect and address dependability issues as the system operates.

Many different patterns exist to address dependability concerns. This task clarifies the nature of the risks and puts into place measures (as defined by the relevant design patterns) that mitigate these risks.

Steps
Identify safety, reliability, and security concerns
This step identifies the dependability concerns to be addressed by the architecture. For safety, this means identifying the safety-relevant hazards. For reliability, it means identifying the services required to be available. For security, it means identifying the assets vulerable to attack or theft. In all cases, it also means to quantify the degree of dependability required of the system.
Analyze control measures
This step analyzes the proposed solutions to ensure that they provide adequate risk mitigation and meet the other, possibly opposing, design constraints in an optimal way. This analysis is often done in the form of an FTA (safety), FEMA (reliabilty) and asset and threat analysis (security).
Integrate dependabilty patterns into architecture
This step elaborates the architecture to include the dependabiltiy design patterns, that is, implement the control measures at the architectural level.
Select design solutions to add control measures to mitigate risks
Based on the nature of the risks and the other design constraints, different design patterns may be more optimal than others. This step selects one or more such patterns. See DOU02 for more information on safety-related design patterns.
Review the hazard analysis
The hazard analysis is usually initially created during requirements definition (see Task: Manage Dependabilty Requirements). This document initially identifies hazards, risks, basic faults, and (possibly) control measure meant to mitigate the risks.
Review reliability Analysis
The reliability analysis identifies the services required to be highly available and their reliability, usually measured either as Mean-Time Between Failures (MTBF) or as availability. This document may require updating based on the measures added to the architecture.
Review threat analysis
The threat analysis identifies the assets to be protected, their vulnerabilities and the control measures used to prevent, identify, and/or recover from threats. This analysis may require updating based on the architectural measures put into place to address security and information assurance.
More Information
Concepts
Guidelines