What is the maximum time from last known normal?

The maximum time from last known normal, also known as the maximum allowable downtime (MAD), is the maximum amount of time a system, service, or component can be non-functional without causing unacceptable consequences or disruptions.

For critical systems or services, maximum downtime is often measured in seconds or minutes, as any longer period of downtime could result in significant financial losses, data corruption, or safety concerns.

In non-critical systems or services, the maximum downtime can be hours, days, or even weeks, depending on the nature of the service and the impact of downtime on operations or users.

To determine the maximum allowable downtime, organizations must consider factors such as the criticality of the system or service, the potential impact of downtime on operations, the cost of downtime, and any legal or regulatory requirements. By setting a maximum allowable downtime, organizations can establish clear expectations for uptime, identify potential vulnerabilities, and implement measures to minimize downtime and mitigate risks.