MTTR stands for Mean Time to Repair; a Key Performance Indicator (KPI) that represents the average time required to restore a system to functionality after an incident. There are other incident metrics used alongside MTTR in order to assess the performance of DevOps and ITOps, gauge the effectiveness of security processes, evaluate the effectiveness of security solutions, and measure the maintainability of systems.
Expectations of MTTR are typically set by service level agreements by third-party agreements, even though repair times are not guaranteed because some incidents are more complex than others. MTTR is highly dependent on unique factors relating to the size and type of infrastructure, as well as the size and skills of the ITOps and DevOps teams. As such, comparing the MTTR of different organizations does not deliver any conclusive results. Different businesses have to determine which metrics will best serve their purposes and how it will put them into action in their unique environment.
Difference Between Common Failure Metrics
There are many incident metrics to choose from due to the fact that modern enterprise systems are complicated and they can fail in numerous ways.
Mean Time to Identify (MTTI): tracks the number of business hours between the moment an alert is triggered and the moment the cybersecurity team begins to investigate that alert. It is very helpful in understanding if alert systems are effective and if security teams are staffed to the necessary capacity. A high MTTI trends in the wrong direction and shows that a cybersecurity team is experiencing alert fatigue.
Mean Time to Recovery (MTTR): MTTR refers to the average time it takes in business hours between the start of an incident to the time it completely recovers back to normal operations. Using this metric helps you to understand the effectiveness of the DevOps and ITOps teams and identify opportunities to improve their processes and capabilities.
Mean Time to Resolve: it's the average time between the first alert until the incident post analysis. It includes the time spent to ensure that the failure does not reoccur, and it is measured in business hours.
Mean Time Between Failures (MTBF): it measures system readability and availability. MTBF is used by ITOps teams to understand which system of components are performing well and which need to be evaluated for repair or replacement. Checking the MTBF enables penetrative maintenance, minimizes reactive maintenance, reduces total downtime, and allows teams to prioritize their workload effectively. MTBF is calculated by tracking the number of hours that passed between system failures in the ordinary course of operations over a period of time, then calculating the average.
Mean Time to Failure (MTTF): it is a way of looking at uptime vs. downtime. While MTBF focuses on repairability, MTTF focuses on failures that cannot be repaired. It predicts the lifespan of systems but it is not a good fit for every system. Systems with long lifespans are not good subjects for MTTF metrics because they have a long lifespan such that when they are finally replaced, the replacement usually is a completely different type of system due to technological advances.
Benefits of MTTR for DevOps and ITOps
- Reduces unplanned downtime and shortens breakout time.
- Supporta a better culture within ITOps teams.
- When done right, it includes post-incident analysis which informs a feedback loop that leads to better software builds in the future.
- Encourages fixing of bugs early in the SDLC process.
How to calculate MTTR
Add up the total unplanned repair time spent on a system within a particular time frame and divide the result by the total number of relevant incidents.
Each minute spent repairing the most impactful systems is worth an hour of minutes spent repairing less impactful systems.