Final answer:
The mean time needed to bring the system back up to normal operation is called the mean time to repair (MTTR). It includes the time required to diagnose, fix, and test the system.
Step-by-step explanation:
The time needed to bring the system back up to normal operation is typically referred to as the mean time to repair (MTTR).
The MTTR includes the time required to diagnose, fix, and test the system to ensure it is functioning properly.
For example, if a system fails and it takes an average of 2 hours to fix and bring it back up, the MTTR would be 2 hours.