Back

high availability (HA)

High availability refers to the ability of a system to operate continuously without failing for a designated period of time. It is designed to ensure that the system meets an agreed-upon operational performance level, often expressed as a percentage of uptime. The widely held standard for HA is known as “five-nines” availability, meaning the system is available 99.999% of the time[2][5]. HA systems are typically used in industries where it is critical that the system remains operational with minimal downtime.

HA is achieved through redundancy, which allows a system to quickly recover from a component failure by failing over to a redundant component. This means that if one part of the system fails, another part can take over with minimal performance impact. HA systems are designed to minimize downtime and avoid loss of service, but they do not necessarily prevent a service interruption[1][2][5][7][8][11].

Compare to: fault tolerant

Citations:

[1] https://www.linkedin.com/pulse/high-availability-vs-fault-tolerance-jon-bonso

[2] https://www.techtarget.com/searchdatacenter/definition/high-availability

[3] https://www.imperva.com/learn/availability/fault-tolerance/

[4] https://www.ibm.com/docs/en/powerha-aix/7.2?topic=aix-high-availability-versus-fault-tolerance

[5] https://www.cisco.com/c/en/us/solutions/hybrid-work/what-is-high-availability.html

[6] https://www.fortinet.com/resources/cyberglossary/fault-tolerance

[7] https://www.spiceworks.com/it-security/vulnerability-management/articles/high-availability-fault-tolerance-comparison/

[8] https://us.sios.com/resource/high-availability/

[9] https://en.wikipedia.org/wiki/Fault_tolerance

[10] https://www.reddit.com/r/aws/comments/xz45m5/what_is_the_difference_between_high_availability/