Configuring an alert for percentiles

Configure an alert for when percentiles exceed a defined threshold.

Procedure

Select the Alerts menu.
In the Active Alerts dialog, select Manage Alerts. When the Manage Alert Rules dialog appears, select Add Alert.
In the Notify me when menu, select the percentile option for which you want to create an alert.
Select above or below for the milliseconds/operation (ms/op) threshold.
Set the duration of the condition before an alert is triggered.
In OpsCenter 6.7.6 and earlier, this option sets the histogram aggregation window. If the threshold is exceeded within the histogram aggregation window, an alert is immediately triggered. This alert continues to be triggered until the percentile value falls back within the acceptable threshold.

In OpsCenter 6.7.7 and later, this option determines how long the percentile must exceed the threshold before an alert is triggered.
Set the percentile for which you want to track.

Note: The current percentile shows the ms/op for the previous minute for the selected percentile.
Set the Histogram Aggregation Window.

In OpsCenter 6.7.7 and later, the configurable histogram aggregation window and duration are separate.

Percentiles are calculated based on all of the data points within the specified histogram aggregation window. To create an alert that is more sensitive to spikes, increase the histogram aggregation window.

Note: DataStax recommends a one-minute histogram aggregation window to align with the displayed current value and dashboard graphs.
Select the notification frequency of the alert from the Notify every list.
Select Save Alert.
The configured percentiles alert appears in the Manage Alert Rules dialog.