Key Characteristics
Reliability
The ability of the system to deliver services conforming to specification. Concerned with the number of times a service fails to deliver specified services.
Availability
How likely the system is available to deliver services when requested. Especially important for real-time systems and “non-stop systems” which must run continously.
Maintainability
The capacity of the system to evolve or adapt to new requirements. Also considers the ease of repairing the system after a failure has been discovered.
Safety
The ability of the system to operate without catastrophic failure, i.e. to deliver its services in such a way that human life or the system’s environment will not be damaged.
Security
How the system protects itelf against accidental or deliberate damage. Affects other attributes as a security failure can compromise reliability, availability and safety.
Challenges
Integration of “off-the-shelf” components
Off-the-shelf systems are not designed with criticality in mind, yet their low cost and other advantages make them critical to business operations. Therefore, devising a way to safely incorporate them in critical systems becomes a crucial business requirement.
Operations Design
As automated systems become more complex, there is an increasing chance of operational errors. Designing systems that either avoid this or become proportionally more resilient is an absolute necessity but non-trivial.
Achieving rapid delivery of critical systems
Organisational requirements are constantly increasing for rapid system development, but critical systems development is tipically lengthy. It is imperative to reconciliate these two distinct realities through formal and professional systems engineering.
Reliability Models
Fail-operational systems
Continue to operate when their control systems fail. Examples of these include elevators, the gas thermostats in most home furnaces, and passively safe nuclear reactors.
Fault-tolerant systems
Avoid service failure when faults are introduced to the system. The normal method to tolerate faults is to have several computers continually test the parts of a system, and switch on hot spares for failing subsystems
Fail-secure systems
Maintain maximum security when they can not operate. For example, while fail-safe electronic doors unlock during power failures, fail-secure ones will lock, keeping an area secure.
Fail-Passive systems
Continue to operate in the event of a system failure. An example includes an aircraft autopilot.
Fail-safe systems
Become safe when they cannot operate. Many medical systems fall into this category.
3
Yearly cost of IT failures worldwide (in USD)
106
Collective downtime across all website outages in 2014
Typical cost of downtime per hour by Industry
(in millions of USD)
Brokerage
Energy
Telecom
Industry
Retail
Health
[Sources: Vision Solutions, Assessing the Financial Impact of Downtime]
Typical cost of downtime per hour by Industry
(in millions of USD)
Brokerage
Energy
Telecom
Industry
Retail
Health
[Sources: Vision Solutions, Assessing the Financial Impact of Downtime]
Industries
Aerospace and Defense
Higher performance, increased capability, improved reliability and uncompromised safety are among the key factors that drive technical advances in aerospace and defence. Integrating software and safety engineering processes for the development of air traffic control software, providing guidance for safety assurance of command and control systems, developing safety requirements for UAVs, and evaluating safety aspects of communication systems on airborne platforms are some examples of critical system engineering.
Medical Technology
Software intensive systems are an increasingly vital part of health care delivery both with respect to the management and distribution of patient data and the life critical real-time operation of complex medical devices. Standards such as ISO 14971 guide medical device companies in addressing the challenge of balancing residual risks with the anticipated benefits of using an innovative technology to treat patients.
Utilities
The wellbeing and security of all societies depends on the availability of critical infrastructure, such as the electric grid, water supply infrastructure, oil and gas facilities and public warning systems, which are often managed using critical systems such as Integrated Control Systems (ICS) or other similar types of control systems. These critical systems are undergoing modernization to improve safety, security and reliability. Modernization efforts also aim to increase efficiency by means of automation and remote operation.
Benefits
Cost Reduction
When compared to the disastrous financial impact that systems failure can produce, guaranteeing that critical systems can avoid or tolerate failure is a smart investment.
Flexibility
Critical systems can be adapted to a customer’s specific business agility needs to better achieve its advantages.
Availability Increase
Using advanced critical system engineering know-how and mission-critical support, military-grade availability can be achieved on production systems.
99
impact cost reduction
3
more flexible
90
availability increase