Can you explain what the term RTO means and what role it plays in ensuring system fault tolerance?

RTO (Recovery Time Objective) is the target time for system recovery after a failure or incident. It defines the maximum allowable downtime during which a service or system can be unavailable without critical business impact.

In the context of fault tolerance, RTO helps plan recovery measures: backup, disaster recovery, automatic restoration, etc. The shorter the RTO, the faster the system should recover after a failure.

For example, if an online store has an RTO of 1 hour, it means that after a failure, the service must be restored and operational no later than an hour later; otherwise, the business will incur significant losses.

Thus, RTO is a key parameter for building reliable and fault-tolerant systems, allowing a balance between infrastructure costs and availability requirements.