Skip to main content

Understanding Key Metrics in System Reliability: Mean Time to Restore and Change Failure Rate


In the ever-evolving landscape of system reliability and incident management, two metrics stand out for their critical importance: Mean Time to Restore (MTTR) and Change Failure Rate (CFR). These metrics not only gauge the health and efficiency of systems but also guide organizations in enhancing their operational resilience.

Mean Time to Restore (MTTR)

MTTR measures the average time taken to recover from an incident. This metric is vital in assessing the availability and reliability of key systems. The primary goal of tracking MTTR is to reduce recovery time, thereby improving system availability. However, it’s important to balance the focus between rolling back to a previous state and rolling forward to deliver business value. Overemphasis on rollback can skew the MTTR and detract from the forward progression of business objectives.

Change Failure Rate (CFR)

CFR, on the other hand, indicates the percentage of changes that result in degraded service and subsequently require remediation. This metric is averaged over a period and includes all changes that needed fixing. The aim here is to enhance reliability by improving tooling and processes early in the Software Development Life Cycle (SDLC) and deployment lifecycle. A critical aspect to monitor while measuring CFR is the system integration dependencies and failure detection capabilities. It’s essential to recognize that even if your systems are functioning reliably, they can still impact other dependent systems either downstream or upstream.


In conclusion, MTTR and CFR are indispensable metrics for any organization focused on system reliability and incident management. By effectively measuring and managing these metrics, businesses can significantly improve their system availability and reliability, ensuring a more resilient and efficient operational environment.