Business Continuity of a company are defined according to RTO and RPO. An availability strategy of an information service should be defined according to the following 4 time segments:

• From T ^­­ ₀to T ^­­ ₁: this time interval is between the time the incident occurs and the time we have the latest copy of the backed-up data. This interval thus corresponds to the RPO.
• From T ^­ ₁to T ^­­ ₂: this time interval starts from the moment the incident occurs and ends when the recovery process is completed. This process is activated by an operator or control software. There is a service unavailability during this period of time.
• From T ^­­ ₂to T ^­­ ₃: this time interval determines the time of operations in degraded mode of the system. It matches to the time required to cope with a new incident leading to a service interruption.
• From T ^­­ ₃to T ^­­ ₄: this time interval determines the time required to return to normal production, without degradation of service or performance.