Understand PI Analysis Service performance counters

PI Analysis Service creates the following performance counters that can be used for troubleshooting.

• AFValues Written: Number of AF values published since the start of service

• Analyses in Error: Number of analyses currently in error

• Analyses Running: Number of running analyses

• Analyses Suspended: Number of suspended analyses

• Cache Hit Count: Total number of data access calls that were serviced by the data cache since the start of service

• Cache Missed Count: Total number of data access calls that could not be serviced by the data cache since the start of service

• Evaluation Count: Number of successful evaluations since the start of service

• Evaluation Error Count: Number of evaluation errors since the start of service

• Evaluation Out of Order Ignored Count: Number of evaluations ignored, owing to their having an out of order time stamp, since the start of service

• Evaluation Skipped Count: Number of skipped evaluations since the start of service. Large and growing number of skipped evaluations is a common symptom of performance issues.

• Event Frames Written: Number of event frames published since the start of service

• Events Cached: Total number of events currently cached for all analysis input attributes

• Events Processed: Total number of events retrieved for all analysis input attributes since the start of service

• Maximum Latency: Maximum among the latest latency values reported for all analyses. Latency is defined as the amount of time (in milliseconds) from receiving a trigger event to executing and publishing the analysis results for that trigger event. Large and growing number of maximum latency is a common symptom of performance issues. This value also includes the time that PI Analysis Service waits before evaluating calculations in order to make sure that data for all inputs is available. This wait time can be configured by editing the parameter CalculationWaitTimeInSeconds. The default value for this property is 5 seconds. For more information, see PI System Explorer topic Analysis service configuration.

• Recalculation Requests Completed: Number of recalculation requests completed since the start of service

• Recalculation Requests Queued: Number of recalculation requests pending