Device and Sensor Setup > Sensor Settings

PRTG Manual: Probe Health Sensor

The Probe Health sensor monitors internal PRTG parameters. It shows the status of the probe system. The sensor checks various parameters of the probe system that can affect the quality of the monitoring results.

For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Probe Health Sensor

Sensor in Other Languages

Dutch: Probe Status
French: État de la sonde
German: Zustand der Probe
Japanese: プローブ正常性
Portuguese: Funcionamento da sonda
Russian: Работоспособность зонда
Simplified Chinese: 探针健康状况
Spanish: Salud de sonda

Remarks

PRTG automatically creates this sensor. You cannot delete it.
You can only create this sensor on a probe device, either a local probe device or a remote probe device.

This sensor has a very low performance impact.

See the Knowledge Base: My probe system is running out of disk space. What can I do?

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.

Setting	Description
Sensor Name	Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets. If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?
Parent Tags	Shows tags that the sensor inherits from its parent device, parent group, and parent probe. This setting is shown for your information only and cannot be changed here.
Tags	Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited. It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>). The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor: probehealthsensor
Priority	Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority () to the highest priority ().

Sensor Display

Setting	Description
Primary Channel	Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor. You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.
Graph Type	Define how different channels are shown for this sensor: Show channels independently (default): Show a graph for each channel. Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic. You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).
Stack Unit	This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Setting

Description

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

Show channels independently (default): Show a graph for each channel.
Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Inherited Settings

By default, all of the following settings are inherited from objects that are higher in the hierarchy. You should change them centrally in the root group settings if necessary. To change a setting for this object only, click under the corresponding setting name to disable the inheritance. You then see the options described below.

For more information, see section Inheritance of Settings.

Scanning Interval

Click to interrupt the inheritance.

Setting	Description
Scanning Interval	Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from: 30 seconds 60 seconds 5 minutes 10 minutes 15 minutes 30 minutes 1 hour 4 hours 6 hours 12 hours 1 day You can change the available intervals in the system administration on PRTG on premises installations.
If a Sensor Query Fails	Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows the Warning status. Choose from: Set sensor to down immediately: Set the sensor to the Down status immediately after the first request fails. Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to the Warning status after the first request fails. If the second request also fails, the sensor shows the Down status. Set sensor to warning for 2 intervals, then set to down: Set the sensor to the Down status only after the third request fails. Set sensor to warning for 3 intervals, then set to down: Set the sensor to the Down status only after the fourth request fails. Set sensor to warning for 4 intervals, then set to down: Set the sensor to the Down status only after the fifth request fails. Set sensor to warning for 5 intervals, then set to down: Set the sensor to the Down status only after the sixth request fails. Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show the Down status. It is not possible to immediately set a WMI sensor to the Down status, so the first option does not apply to these sensors. All other options can apply. If you define error limits for a sensor's channels, the sensor immediately shows the Down status. None of the interval options apply. If a channel uses lookup values, the sensor immediately shows the Down status. None of the interval options apply.

Setting

Description

Scanning Interval

Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:

30 seconds
60 seconds
5 minutes
10 minutes
15 minutes
30 minutes
1 hour
4 hours
6 hours
12 hours
1 day

You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows the Warning status. Choose from:

Set sensor to down immediately: Set the sensor to the Down status immediately after the first request fails.
Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to the Warning status after the first request fails. If the second request also fails, the sensor shows the Down status.
Set sensor to warning for 2 intervals, then set to down: Set the sensor to the Down status only after the third request fails.
Set sensor to warning for 3 intervals, then set to down: Set the sensor to the Down status only after the fourth request fails.
Set sensor to warning for 4 intervals, then set to down: Set the sensor to the Down status only after the fifth request fails.
Set sensor to warning for 5 intervals, then set to down: Set the sensor to the Down status only after the sixth request fails.

Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show the Down status. It is not possible to immediately set a WMI sensor to the Down status, so the first option does not apply to these sensors. All other options can apply.

If you define error limits for a sensor's channels, the sensor immediately shows the Down status. None of the interval options apply.

If a channel uses lookup values, the sensor immediately shows the Down status. None of the interval options apply.

Access Rights

Click to interrupt the inheritance.

Setting	Description
User Group Access	Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights: Inherited: Inherit the access rights settings of the parent object. No access: Users in this user group cannot see or edit the sensor. The sensor neither shows up in lists nor in the device tree. Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings. Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings. Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings. For more details on access rights, see section Access Rights Management.

Setting

Description

User Group Access

Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:

Inherited: Inherit the access rights settings of the parent object.
No access: Users in this user group cannot see or edit the sensor. The sensor neither shows up in lists nor in the device tree.
Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings.
Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings.

For more details on access rights, see section Access Rights Management.

Channel Unit Configuration

Click to interrupt the inheritance.

Setting	Description
Channel Unit Types	For each type of channel, select the unit in which PRTG displays the data. If you define this setting on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available): Bandwidth Memory Disk File Custom Custom channel types are only available on sensor level.

Setting

Description

Channel Unit Types

For each type of channel, select the unit in which PRTG displays the data. If you define this setting on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):

Bandwidth
Memory
Disk
File
Custom

Custom channel types are only available on sensor level.

Channel List

Which channels the sensor actually shows might depend on the monitored device, the available components, and the sensor setup.

Channel	Description
CPU Load	The CPU load in percent that the probe process causes. Extensive CPU load can lead to false, incomplete, and incorrect monitoring results. This value should usually stay below 50%.
Downtime	In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status in percent.
Handles	The counter for the data structures of the operating system. It is responsible for internal resource management. Investigate obviously increasing values that occur repeatedly.
Health	The sum of the probe state as a value between 100% (healthy) and 0% (failing). Investigate frequent or repeated health values below 100%. This channel is the primary channel by default.
Interval Delay non-WMI&SNMP	The interval delay in percent for all sensors that are not of the type Simple Network Management Protocol (SNMP) or Windows Management Instrumentation (WMI). If this value is above 0%, try to increase the scanning intervals or distribute your sensors among probes.
Interval Delay SNMP	The interval delay in percent for SNMP sensors. If this value is above 0%, there are probably too many SNMP v3 sensors that are very slow. In this case, try to increase the scanning intervals or distribute the sensors among probes.
Interval Delay WMI	The interval delay in percent for WMI sensors. If this value is above 0%, WMI sensors were not able to check the target device according to their interval. 100% means that WMI sensors are checked with twice their interval on average. For values above 0%, try to increase the scanning intervals or distribute the sensors among probes to keep the number of WMI sensors per probe below 120 (with a 60-second scanning interval) or 600 (with a 300-second scanning interval).
Lost Flow Packets	The number of lost xFlow (NetFlow, jFlow, sFlow, IPFIX) packets in percent. The higher this value, the less xFlow packages PRTG can handle. Usually, this value should be 0%. Investigate increasing values.
Memory Usage	The amount of memory that is used by the PRTG probe service as reported by the memory manager. Investigate obviously increasing values that occur repeatedly. If the value is constantly above 2 GB, this indicates that PRTG runs at its limits. In this case, you should distribute some sensors among remote probes.
Message Queue	The number of monitoring results that have not been processed by the core yet. This value should usually stay below 1/10 of the sensor count.
Open Requests	The number of active monitoring requests. This value should stay below the maximum of 500 open requests.
Syslog Buffer	The number of buffered syslog packages. Usually, this value should be 0 (or very low). Investigate increasing values.
Syslog Drop	The number of dropped syslog packages
Threads	The number of program parts that are running simultaneously. This value can increase with heavy load. Usually, the number should not exceed 100.
Toplist Memory	The amount of RAM that the Toplists on this probe are using. Stay below 1 GB memory usage (depending on the available memory on the probe system). If necessary, reduce the number of Toplists or distribute them among probes.
Trap Buffer	The number of buffered SNMP traps. Usually, this value should be 0 (or very low). Investigate increasing values.