What is this?

This knowledgebase contains questions and answers about PRTG Network Monitor and network monitoring in general.

Learn more

PRTG Network Monitor

Intuitive to Use. Easy to manage.
More than 500,000 users rely on Paessler PRTG every day. Find out how you can reduce cost, increase QoS and ease planning, as well.

Free Download

Top Tags

View all Tags

MySQL v2 Sensor with RDS Instance: Channel Graph doesn't reset



PRTG version = Sensor = MySQL v2

We're monitoring a MariaDB RDS instance


  1. Data
    1. SQL Query File: custom-file.sql
    2. Handle DBNull in Channel Values as: Number 0
    3. Select Channel Value by: Column Number
    4. Sensor Channel #1 Name: Count
    5. Sensor Channel #1 Column Number: 0
    6. Sensor Channel #1 Unit: Count
    1. Limits: Enable alerting based on limits
    2. Upper Error Limit (#): 0
    1. State Trigger:
      1. When sensor state is Down: send alert
      2. When sensor state is Up: send alert


  1. Custom-file.sql runs a select statement to get a count from a table
  2. The sql statement works and provides the correct value - we're simply running tests and updating the db to toggle the output to be expected
  3. the sensor is reporting the accurate count, and sending Down/Up alerts as expected
  4. the sensor is also reporting Red/Green correctly based on whether the count crosses limit

Channel graph color does not reset after alert clears. The sensor resets to an Up status/Green, but, the channel graph remains Red. This leads to a confusing visual when looking into the sensor specifically.


mysql-v2-sensor prtg rds

Created on Nov 6, 2018 3:50:39 PM

Last change on Nov 7, 2018 1:08:34 PM by  Stephan Linke [Paessler Support]

1 Reply



Thanks for the thorough description of the issue. Am I getting this correctly, that the main issue here is the channel gauge being red? This is due to the upper error limit being set to 0. You could use a lookup that causes the gauge to look differently:

Using lookups in PRTG

Let me know if that works for you :)

PRTG Scheduler | PRTGapi | Feature Requests | WMI Issues | SNMP Issues

Kind regards,
Stephan Linke, Tech Support Team

Created on Nov 7, 2018 1:11:22 PM by  Stephan Linke [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.