Single point of failure
Encyclopedia
A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working. They are undesirable in any system with a goal of high availability
or reliability
, be it a business practice, software application, or other industrial system.
Redundancy can be achieved at various levels. For instance, the owner of the tree care company may have spare parts ready for the repair of the wood chipper, in case it fails. At a higher level, he may have a second wood chipper that he can bring to the job site. Finally, at the highest level, he may have enough equipment available to completely replace everything at the work site in the case of multiple failures.
The assessment of a potential SPOF involves identifying the critical components of a complex system that would provoke a total systems failure in case of malfunction
. Highly reliable systems should not rely on any such individual component.
In a high-availability server
cluster, each individual server may attain internal component redundancy by having multiple power supplies, hard drives, and other components. System level redundancy could be obtained by having spare servers waiting to take on the work of another server if it fails.
Since a data center is often a support center for other operations such as business logic, it represents a potential SPOF in itself. Thus, at the site level, the entire cluster may be replicated at another location, where it can be accessed in case the primary location becomes unavailable.
management.
Design structures that create single points of failure include bottlenecks
and series circuits (in contrast to parallel circuits).
Applications:
In literature:
High availability
High availability is a system design approach and associated service implementation that ensures a prearranged level of operational performance will be met during a contractual measurement period....
or reliability
Reliability engineering
Reliability engineering is an engineering field, that deals with the study, evaluation, and life-cycle management of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. It is often measured as a probability of...
, be it a business practice, software application, or other industrial system.
Overview
Systems can be made robust by adding redundancy in all potential SPOFs. For instance, the owner of a small tree care company may only own one wood chipper. If the chipper breaks, he may be unable to complete his current job and may have to cancel future jobs until he can obtain a replacement.Redundancy can be achieved at various levels. For instance, the owner of the tree care company may have spare parts ready for the repair of the wood chipper, in case it fails. At a higher level, he may have a second wood chipper that he can bring to the job site. Finally, at the highest level, he may have enough equipment available to completely replace everything at the work site in the case of multiple failures.
The assessment of a potential SPOF involves identifying the critical components of a complex system that would provoke a total systems failure in case of malfunction
Malfunction
A malfunction is when something functions wrongly or does not function at all.Some types of malfunctions are:*Malfunction , malfunction of a parachute*Sexual malfunction, also called "sexual dysfunction"**See also dyspareunia...
. Highly reliable systems should not rely on any such individual component.
Computing
In computing, redundancy can be achieved at the internal component level, at the system level (multiple machines), or site level (replication).In a high-availability server
Server (computing)
In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...
cluster, each individual server may attain internal component redundancy by having multiple power supplies, hard drives, and other components. System level redundancy could be obtained by having spare servers waiting to take on the work of another server if it fails.
Since a data center is often a support center for other operations such as business logic, it represents a potential SPOF in itself. Thus, at the site level, the entire cluster may be replicated at another location, where it can be accessed in case the primary location becomes unavailable.
Other fields
The concept of a single point of failure has also been applied to fields outside of engineering, computers, and networking, such as corporate supply chainSupply chain
A supply chain is a system of organizations, people, technology, activities, information and resources involved in moving a product or service from supplier to customer. Supply chain activities transform natural resources, raw materials and components into a finished product that is delivered to...
management.
Design structures that create single points of failure include bottlenecks
Bottleneck
A bottleneck is a phenomenon where the performance or capacity of an entire system is limited by a single or limited number of components or resources. The term bottleneck is taken from the 'assets are water' metaphor. As water is poured out of a bottle, the rate of outflow is limited by the width...
and series circuits (in contrast to parallel circuits).
See also
Concepts:- Reliability theoryReliability theoryReliability theory describes the probability of a system completing its expected function during an interval of time. It is the basis of reliability engineering, which is an area of study focused on optimizing the reliability, or probability of successful functioning, of systems, such as airplanes,...
- RedundancyRedundancyRedundancy may refer to:* Redundancy * Redundancy * Redundancy * Redundancy * Redundancy * Data redundancy* Gene redundancy* Logic redundancy...
Applications:
- Reliability engineeringReliability engineeringReliability engineering is an engineering field, that deals with the study, evaluation, and life-cycle management of reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time. It is often measured as a probability of...
- Safety engineeringSafety engineeringSafety engineering is an applied science strongly related to systems engineering / industrial engineering and the subset System Safety Engineering...
In literature:
- Achilles' heelAchilles' heelAn Achilles’ heel is a deadly weakness in spite of overall strength, that can actually or potentially lead to downfall. While the mythological origin refers to a physical vulnerability, metaphorical references to other attributes or qualities that can lead to downfall are common.- Origin :In Greek...
- Hamartia#"Tragic flaw"