Synthetic calculations

Dynatrace uses specific formulas to calculate metric values and generate problems based on these metrics.

Availability

Availability calculation for a synthetic monitor isn't based on the number of successful executions but on the length of time that a monitor is considered to be UP. Dynatrace stores time stamps of state changes—UP, DOWN, and UNMONITORED.

The timespan covered by successive successful monitor executions is considered to be uptime (UP). The time between the last successful execution and the first failed execution is also considered to be uptime (UP). Likewise, the timespan covered by successive failed executions is considered to be downtime (DOWN). The time between the last failed execution and the first successful execution is considered to be downtime (DOWN). This is illustrated in the image below.

The time that a monitor spends in the UNMONITORED state isn't considered in availability calculations.

  • Uptime is the length of time in ms during which a synthetic monitor is in state UP.
  • Downtime is the length time in ms during which a synthetic monitor is in state DOWN.
  • Availability % per location is Uptime / (Uptime + Downtime) x 100.
  • Overall availability of a monitor is the sum of availability % per location / number of locations.

Availability is stored as a percentage with two decimal places.

Availability calculation

Maintenance windows

Maintenance windows can be excluded from availability calculation for synthetic monitors (even retroactively). A global setting enables you to always exclude maintenance windows from availability calculation—go to Settings > Web and mobile monitoring > Synthetic availability to access it.

Custom charts and the Metrics API provide availability metrics with the option of including or excluding maintenance windows.

Retries

Retry on error is automatically enabled for browser monitors. Discarded executions are ignored in availability calculations.

  • Browser monitors: Automatic retry (first unsuccessful execution is ignored)
  • HTTP monitors: No retries

Key performance metrics

Total duration is calculated as a summation of the User action duration of the load and XHR actions in a monitor. Other key performance metric values are averages, calculated separately for load actions and XHR actions.

Performance problems

Dynatrace generates a performance threshold violation problem if a monitor at a given location violates any of the defined performance thresholds in 3 of the 5 most recent executions, unless there is an open maintenance window for the monitor. That is, the violations must occur at the same location. Multiple locations can have such violations and be included in a problem.

A problem is not created, for example, if your monitor runs from 3 locations, and each location has 1 violation.

Many locations, each with 3 violations in the 5 most recent executions, can be part of the same problem if the violations occur around the same time. If the violations are further apart in time, separate problems are generated for each location.

The problem is closed if the performance thresholds aren't violated in the 5 most recent executions at each of the previously affected locations.