Mean time to recovery
In modem software products and services, which are rapidly changing complex systems, failure is inevitable, so the key question becomes: How quickly can service be restored? — Accelerate: The Science of Lean Software and DevOps. IT Revolution Press
Mean time to recovery, or MTTR, is calculated by adding up the total time spent on resolving an incident during any given period and then dividing that time by the number of incidents. This metric is most useful to measure how quickly your organization is able to resolve an incident. In other words, it can give you a sense of how resilient your system is.