Acceptable Downtime

Definition(s):

The maximum elapsed time between a disruption and restoration of needed operational capacity or capability.

Source: ASIS

Acceptable Downtime is the maximum amount of time that a system can be offline or unavailable due to maintenance, upgrades, or other outages before it becomes unacceptable to users.

Glossary: Recovery Time Objective [RTO]
Understanding Recovery Time Objectives: A Key Component in Business Continuity