<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: Core Health Sensor

The Core Health sensor is a probe-dependent sensor that monitors internal PRTG parameters. It shows the status of the PRTG core server and checks various parameters of the PRTG core server that have an impact on the stability of the system.

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

Core Health Sensor

Core Health Sensor

Sensor in Other Languages

  • Dutch: Core Status
  • French: État du serveur central
  • German: Serverzustand
  • Japanese: コアの正常性
  • Portuguese: Funcionamento do servidor central
  • Russian: Работоспособность базового сервера
  • Simplified Chinese: 核心健康状况
  • Spanish: Salud del servidor central


  • PRTG automatically creates this sensor. You cannot delete it.
  • You can only set up this sensor on a local probe device.
  • This sensor has a very low performance impact.

Basic Sensor Settings

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

Basic Sensor Settings

Basic Sensor Settings



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.

i_round_blueIf 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.

i_round_blueThis setting is for your information only. You cannot change it.


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.

i_round_blueIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

i_round_blueFor performance reasons, it can take some minutes until you can filter for new tags that you added.

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

  • corehealthsensor


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 (i_priority_1) to the highest priority (i_priority_5).

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

Sensor Display

Sensor Display

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 is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

i_round_blueYou can set a different primary channel later by clicking b_channel_primary 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.
    i_round_redYou 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. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Scanning Interval

Click b_inherited_enabled to interrupt the inheritance.

Scanning Interval

Scanning Interval



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
  • 24 hours

i_round_blueYou 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.

i_round_blueSensors 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.

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

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

Access Rights

Click b_inherited_enabled to interrupt the inheritance.

Access Rights

Access Rights



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.

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

Channel Unit Configuration

Click b_inherited_enabled to interrupt the inheritance.

i_round_blueWhich channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.

Channel Unit Configuration

Channel Unit Configuration



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, you can inherit these settings to all sensors underneath. You can set units for the following channel types (if available):

  • Bandwidth
  • Memory
  • Disk
  • File
  • Custom

i_round_blueCustom channel types are only available on sensor level.

Channel List

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



Age of Code

The time that has passed since the last update of your PRTG core server. Update regularly to get the best security and stability for PRTG, as well as the latest features. We recommend that you use the auto-update to automatically get new versions.

Committed Memory

The amount of memory committed to the PRTG core server as reported by the memory manager

Configuration Last Saved

The time passed since the configuration file was last saved successfully. PRTG saves the configuration every 24 hours. If the configuration cannot be saved, PRTG creates a ticket as soon as the saving process has failed, and warns you via this channel after 26 hours. None of your changes to PRTG can be saved if this happens. In this case, restart your PRTG core server to save the file.

CPU Load

The CPU load in percent. Extensive CPU load can lead to false, incomplete, and incorrect monitoring results. This value should usually stay below 50%.


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.

Free Page File Memory

The amount of free page file memory that is 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 running processes. If it gets too low, the system can break down, and at least some applications throw Out of memory errors.

Free Physical Memory

The amount of free physical memory that is available on the system. This is the RAM that is physically built into the computer. If it gets too low, the system becomes very slow and PRTG no longer works in a useful way. Some sensors might not be displayed correctly and show the Unknown status.

Free Virtual Memory

The address space on the system that PRTG can access. PRTG cannot use more memory than reported here, which is independent from free page file and physical memory. On a 32-bit operating system, the maximum is 2 GB (3 GB with special settings under Windows). On a 64-bit operating system, it is 4 GB if PRTG runs as a 32-bit version, and unlimited if it runs as a 64-bit version (PRTG core server only). If the free virtual memory gets too low, PRTG throws Out of memory errors or the message not enough storage to process this command. This message is visible in the Core log.


The counter for the data structures of the operating system. It is responsible for internal resource management. Investigate obviously increasing values that occur repeatedly.


The sum of the core state as a value between 100% (healthy) and 0% (failing). Investigate frequent or repeated health values below 100%.

i_round_blueThis channel is the primary channel by default.

Maintenance Days

The remaining maintenance days of your PRTG on premises license. Renew your maintenance in time to make sure that you get updates for your PRTG on premises installation. PRTG Hosted Monitor instances show a fixed value here for technical reasons.

Notifications in Send Queue

The number of notifications that are in the send queue

Number of State Objects

The number of user-specific state objects that are found in the PRTG core server system's memory

Probe Messages per Second

The number of messages sent per second from all probes to the PRTG core server

Raw Data Buffer

The amount of raw data that is temporarily stored on the physical memory during input/output (I/O) operations on the disk. Usually, this value should be 0 (or very low). Investigate increasing values.


The number of program parts that are running simultaneously. This number can increase with heavy load. Usually, this number should not exceed 100.


i_square_blueKNOWLEDGE BASE

What do the PRTG core memory parameters mean?

What security features does PRTG include?

Sensor Settings Overview

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