What Does High Availability (HA) Mean?
High availability refers to systems that are durable and likely to operate continuously without failure for a long time. The term implies that parts of a system have been fully tested and, in many cases, that there are accommodations for failure in the form of redundant components.
Techopedia Explains High Availability (HA)
A lot of analysis of high availability in a system involves looking for the weakest link, whether that is a specific piece of hardware, or an element of the system, such as data storage. To enable more durable data storage, engineers seeking high availability can use a RAID design. Servers can also be set up to switch responsibilities to a remote server if necessary, in a backup process known as failover.
Although good design factors into high availability, it's also important that each piece of hardware be evaluated for durability. Here, specific metrics from vendors are helpful in determining for exactly how long a piece of hardware is estimated to function in a particular system. Here, metrics like mean time between failures (MTBF) become useful to engineers.