PRTG Manual: Core Health Sensor

The Core Health sensor monitors internal PRTG parameters. It shows the state of the PRTG core server. It is created automatically by PRTG and cannot be deleted. This sensor type checks various parameters of your PRTG core which have an impact on the stability of the system:

  • Health: This index value sums up the core state into a value between 100% (healthy) and 0% (failing). Frequent or repeated health values below 100% should be investigated.
  • CPU Load: This channel shows the current percentage CPU load. Extensive CPU load can lead to false, incomplete, and incorrect monitoring results. This value usually should stay below 50%.
  • Handles: This is a counter for the data structures of the operating system. It is responsible for internal resource management. Repeated obviously increasing values should be investigated.
  • Committed Memory: This channel shows the amount of memory committed to the PRTG core server as reported by the memory manager.
  • Free Page File Memory: This channel shows the amount of free page file memory currently available on the system. Page file memory is aggregated RAM and the size of page file. It is the maximum amount of memory that is available on the system to be used for all currently running processes. If it gets too low the system can crash, at least some applications will throw "Out of memory" errors.
  • Free Physical Memory: This channel shows the amount of free physical memory currently available on the system. This is the RAM that is physically built-in in the computer. If it gets too low the system will become very slow and PRTG is not usable in a reasonable way anymore. It can happen that some sensors will not be displayed correctly in that case, they will appear disabled (grayed out).
  • Free Virtual Memory: This channel shows the accessible address space on the system for PRTG. PRTG cannot use more memory than reported here, independently from free page file and physical memory. On a 32bit OS (operating system) the maximum is 2 GB (3 GB with special settings under Windows); on a 64bit OS it is 4 GB if PRTG is running as 32bit version, and unlimited as 64bit version (only Core). If free virtual memory gets too low, PRTG will throw "Out of memory" errors or the message "not enough storage to process this command" (visible in the Core log).
  • Threads: This channel shows the number of program parts which are currently running simultaneously. This number can increase with heavy load. The number should not exceed 100 in normal operation.

This sensor can be set up on a Probe Device only!

Sensor Settings

On the sensor's details page, click on the Settings tab to change settings.

Note: If not set explicitly in a sensor's settings, it will connect to the IP Address or DNS Name defined in the settings of the parent device the sensor is created on.

Basic Sensor Settings

Sensor Name

Enter a meaningful name to identify the sensor. The name will be shown by default in the device tree and in all alarms.


Enter one or more tags, separated by space or comma. You can use tags to group sensors and use tag-filtered views later on. Tags are not case sensitive. We recommend using the default value. You can add additional tags to it, if you like. Other tags are automatically inherited from objects further up in the device tree. Those are not visible here.


Select a priority for the sensor. This setting determines where the sensor will be placed in sensor lists. Top priority will be at the top of a list. You can choose from one star (low priority) to five stars (top priority).

Sensor Display

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 will always be displayed underneath the sensor's name. The available options depend on what channels are available for this sensor. Note: You can set another primary channel later by clicking on the pin symbol of a channel in the sensor's overview tab.

Chart Type

Define how different channels will be shown for this sensor.

  • Show channels independently (default): Show an own 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 will generate an easy-to-read graph which visualizes the different components of your total traffic. Note: This option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channels Settings settings).

Stack Unit

This setting is only available if stacked graphs are selected above. Choose a unit from the list. All channels with this unit will be 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 following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings. To change a setting for this object, disable inheritance by clicking on the check mark symbol in front of the respective setting name. You will then see the options described below.

Scanning Interval

Scanning Interval

The scanning interval determines the time the sensor waits between two scans. Select a scanning interval (seconds, minutes, or hours) from the list. You can change the available intervals in the system administration.

Access Rights

User Group Access

Define which user group(s) will have access to the object you're editing. A table with user groups and right is shown; it contains all user groups from your setup. For each user group you can choose from the following access rights:

  • Inherited: Use the settings of the parent object.
  • None: Users in this group cannot see or edit the object. The object does not show up in lists and in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree, though not accessible.
  • Read: Users in this group can see the object and review its monitoring results.
  • Write: Users in this group can see the object, review its monitoring results, and edit the object's settings. They cannot edit access rights settings.
  • Full: Users in this group can see the object, review its monitoring results, edit the object's settings, and edit access rights settings.

You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option.

For more details about access rights, please see section User Access Rights.

Channel Unit Configuration

Channel Unit Types

For each type of sensor channel, define the unit in which data is displayed. If defined 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

Note: Custom channel types can be set on sensor level only.

Edit Sensor Channels

In order to change display settings, spike filter, and limits, please switch to the sensor's Overview tab and click on the gear icon of a specific channel. For detailed information, please see Sensor Channels Settings section.


Click on the Notifications tab to change notification triggers. For detailed information, please see Sensor Notifications Settings section.


For more general information about settings, please see Object Settings section.

Sensor Settings Overview

For information about sensor settings, please see the following sections: