Mediatailor metrics in Cloudwatch

Question

I'm looking Mediatailor metrics in Cloudwatch and found that for "Avail" group there are: duration, observedDuration, filledDuration, observedFilledDuracion, fillRate, observedFillRate.

For example for duration, documentation says that duration is a "planned" value and observedDuration is a "observed" value but it is not clear for me. I guess that planned is according with the AD marker in the manifest and observed is from the ad insertion step itself (is it correct?) I guess that "observed" values are more accurate.

Anyway I suppose that "planned" and "observed" values should be similar but usually this is not the case. These are a couple of examples for the values

Filled are similar but duration and fillRate are really different so I don't understand which I should to use

Answer 1

I guess that planned is according with the AD marker in the manifest and observed is from the ad insertion step itself (is it correct?) I guess that "observed" values are more accurate.

Yes, the observed values are what MediaTailor takes action on based on the VAST response from the Ad Decision Server (ADS). Planned is the value received from the Origin via SCTE-35 messaging.

Per the following documentation: https://docs.aws.amazon.com/mediatailor/latest/ug/monitoring-cloudwatch-metrics.html

Duration - The planned total number of milliseconds of ad avails within the CloudWatch time period. The planned total is based on the ad avail durations in the origin manifest.

ObservedDuration - The observed total number of milliseconds of ad avails that occurred within the CloudWatch time period. Avail.ObservedDuration is emitted at the end of the ad avail, and is based on the duration of the segments reported in the manifest during the ad avail.

To continue your example regarding the Duration metric let's say that for a set period of time the Origin server sends a manifest with a single Ad Break for 90 seconds. MediaTailor will perform a request to the ADS asking for 90 seconds of content. The ADS returns a VAST response that includes a 45 second Ad and a 30 second Ad for a total of 75 seconds. MediaTailor will report to CloudWatch that, for the set period of time, the Duration of all Avails planned by the Origin server was 90 seconds, but the Observed Duration provided by the ADS was 75 seconds.

The documentation goes into further detail regarding each metric and even provides some examples.