Merge pull request #2353 from splunk/trangl-o11ydocs-6395-archived-metrics-detectors

Add note on archived metrics in detector

Author: mbechtold-splunk

alerts-detectors-notifications/alerts-and-detectors/create-detectors-for-alerts.rst

@@ -115,11 +115,15 @@ Select alert signals
 
 On the :strong:`Alert signal` tab, define the signal to monitor by entering a metric and corresponding analytics.
 
-If you are creating a detector from scratch, you have to first select the signals you want to monitor. Selecting a signal for a detector is similar to selecting a signal in a chart in the Chart Builder. Enter a metric and select the metric you want to monitor from the list. Add filters or analytics. To learn more, see :ref:`specify-signal`.
+* If you are creating a detector from scratch, you have to first select the signals you want to monitor. Selecting a signal for a detector is similar to selecting a signal in a chart in the Chart Builder. Enter a metric and select the metric you want to monitor from the list. Add filters or analytics. To add more signals, select :guilabel:`Add Metric or Event` or :guilabel:`Add Formula`. You can add events to be displayed on the chart, but you cannot select an event as the signal to be monitored. To learn more, see :ref:`specify-signal`.
 
-If you want to add more signals, select :guilabel:`Add Metric or Event` or :guilabel:`Add Formula`. Note that you can add events to be displayed on the chart, but you cannot select an event as the signal to be monitored.
 
-.. note:: If you are creating a detector :ref:`from a chart<create-detector-from-chart>` or by :ref:`cloning a detector<clone-detector>`, you might not need to add new signals. However, if you do add new signals to the detector, the signals you add are not added to the original chart or detector.
+   .. note:: When you select an archived metric as a signal in your detector, the archived metric can't be report data to your detector and will cause the detector to misfire alerts or stop working. To include an archived metric in detectors, route them to real-time or create exception rules to make them available. For more information, see the :ref:`mpm-rule-routing-exception` section.
+
+* If you are creating a detector :ref:`from a chart<create-detector-from-chart>` or by :ref:`cloning a detector<clone-detector>`, you might not need to add new signals. However, if you do add new signals to the detector, the signals you add are not added to the original chart or detector.
+
+* You can add events to be displayed on the chart, but you can't select an event as the signal to be monitored.
+
 
 .. _compound-conditions: