I suggest to focus on software engineering effectiveness rather than productivity. Key dimensions are code quality, automated testing, and collaboration.
To measure software quality, consider quantitative metrics and qualitative assessments, based on reliability, performance, security, maintainability, usability.
The capacity to withstand a fault without failure is fault tolerance. Monitoring and measuring failure metrics is key to understand what is going on.
In Software engineering, quality is defined as building software correctly and meeting specifications; basically, what the customer has requested.