Availability is a security attribute looking at whether data is accessible in a timely manner for users and processes. The need to access data in an acceptable time can be particularly important in high availability systems which need to be able to operate at all times. Availability is important to security since without it, systems cannot have access to the data that they use to make security decisions with (such as looking at user or process privileges). With availability also having a direct impact upon many businesses ability to perform and make money, availability can be considered to be much more than a security attribute.

System components which do not work, or which need to be modified or upgraded, can present problems for availability. For this reason, administrators of systems which look to have high availability take great care when trying to address these types of issues. However availability could also be caused by issues outside of the power of administrators, such as power outages or hardware failure.

Availability is one of the original attributes of the CIA model.


Last updated: 8 October 2017