<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: WMI Custom String Sensor

The WMI Custom String sensor performs a custom string query via Windows Management Instrumentation (WMI).

Note: Your Windows Management Instrumentation Query Language (WQL) query code must be stored in a file on the system of the probe the sensor is created on: If used on a remote probe, the file must be stored on the system running the remote probe. In a cluster setup, please copy the file to every cluster node.

For this sensor type credentials for Windows systems must be defined for the device you want to use the sensor on.

Note: Sensors using the Windows Management Instrumentation (WMI) protocol have high impact on the system performance! Try to stay below 200 WMI sensors per probe. Above this number, please consider using multiple Remote Probes for load balancing.

For a general introduction to the technology behind WMI, please see Monitoring via WMI section.

Add Sensor

The Add Sensor dialog appears when adding a new sensor on a device manually. It only shows the setting fields that are imperative for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change all settings in the sensor's Settings tab later.

The following settings for this sensor differ in the 'Add Sensor' dialog in comparison to the sensor's settings page:

Custom Query Specific

Channel Name

Enter a name for the channel in which the received data will be presented. The name will be displayed in graphs and tables. Please enter a string. You can change the name later in the sensor's channel settings.

WQL File

Select a file that will be used for this sensor from the drop down menu. It will be executed with every scanning interval. The menu contains WQL scripts from the \Custom Sensors\WMI WQL scripts sub folder of your PRTG installation. Please store your script there. If used on a remote probe, the file must be stored on the system running the remote probe. If used on a cluster probe, you must store the file on all servers running a cluster node! For more information on how to find this path, please see Data Storage section.

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.

Tags

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.

Priority

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).

Custom Query Specific

Namespace

Enter the namespace for the query.

WQL File

Shows the name of the file that this sensor is using. Once a sensor is created this value cannot be changed. It is shown for reference purposes only. If you need to change this, please add the sensor anew.

Placeholder <#PH1>

In your WQL script, you can use up to three placeholders that you can assign a value to using this field. Please enter a string for variable <#PH1> or leave the field empty.

Placeholder <#PH2>

In your WQL script, you can use up to three placeholders that you can assign a value to using this field. Please enter a string for variable <#PH2> or leave the field empty.

Placeholder <#PH3>

In your WQL script, you can use up to three placeholders that you can assign a value to using this field. Please enter a string for variable <#PH3> or leave the field empty.

If Value Changes

Define what shall be done in case the value of this sensor changes. You can choose between:

  • Ignore changes (default): No action will be taken on change.
  • Trigger 'On Change' notification: The sensor will send an internal message indicating that its value has changed. In combination with a Change Trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.

Channel Name

Enter a name for the channel in which the received data will be presented. The name will be displayed in graphs and tables. Please enter a string.

Unit String

Enter a unit for the data that will be received by your script. This is for displaying purposes only. The unit will be displayed in graphs and tables. Please enter a string.

Multiplication

Define with which value the received values will be multiplied by. By default, this is set to 1 in order to not change the received values. Please enter an integer, a decimal value, or leave the field empty.

Division

Define with which value the received values will be divided by. By default, this is set to 1 in order to not change the received values. Please enter an integer, a decimal value, or leave the field empty.

Response Must Include

Define which string must be part of the data that is received form the WMI object. You can either enter plain text or a Regular Expression. If the data does not include the search pattern, the sensor will be set to an error state. Please enter a string or leave the field empty.

Response Must Not Include

Define which string must not be part of the data that is received form the WMI object. You can either enter plain text or a Regular Expression. If the data does include the search pattern, the sensor will be set to an error state. Please enter a string or leave the field empty.

For Keyword Search Use

Define in which format you have entered the search expression in the field above.

  • Plain Text: Search for the string as plain text. The characters * and ? work here as placeholder, whereas * stands for no or any number of characters and ? stands for exactly one character (as known from Windows search). This behavior cannot be disabled, so the literal search for these characters is not possible with plain text search.

Maximum Length of String

Define the maximum allowed length of the string that will be received from the WMI object. If it is longer than this value, the sensor will be set to an error status. Please enter an integer value or leave the field empty.

Extract Number Using Regular Expression

Define if you want to filter out a numeric value from the string received from the WMI object. You can convert this into a float value, in order to use it with channel limits (see Sensor Channels Settings).

  • No extraction: Do not extract a float value. Use the result as a string value.
  • Extract a numeric value using a regular expression: Use a regular expression to identify a numeric value in the string and convert it to a float value. Define below. See also the example below.

Regular Expression

This setting is only visible if number extraction is enabled above. Enter a Regular Expression to identify the numeric value you want to extract from the string returned by the WMI object. You can use capturing groups here. Make sure the expression returns numbers only (including decimal and thousands separators). The result will be further refined by the settings below.

Index of Capturing Group

This setting is only visible if number extraction is enabled above. If your regular expression uses capturing groups, please specify which one will be used to capture the number. Please enter an integer value or leave the field empty.

Decimal Separator

This setting is only visible if number extraction is enabled above. Define which character is used as decimal separator for the number extracted above. Please enter a string or leave the field empty.

Thousands Separator

This setting is only visible if number extraction is enabled above. Define which character is used as thousands separator for the number extracted above. Please enter a string or leave the field empty.

Sensor Result

Define what will be done with the results the sensor receives. Choose between:

  • Discard sensor result: Do not store the results.
  • Write sensor result to disk (Filename: "Result of Sensor (ID].txt"): Store the last result received to the "Logs (Sensors)" directory (on the Master node, if in a cluster). This is for debugging purposes. The file will be overridden with each scanning interval. For information on how to find the folder used for storage, please see Data Storage section.

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.

When a Sensor Reports an Error

With this setting, you can define the number of scanning intervals a sensor has to report an error until the sensor will be set to a Down status. The sensor can try reaching a device several times, depending on your setup you can specify here, to help avoid false alarms if the monitored device has only temporary issues. For previous scanning intervals with failed requests, the sensor will show a Warning status. Choose between:

  • Set sensor to "down" immediately: The sensor will show an error after the first failed request.
  • Set sensor to "warning" for 1 interval, then set to "down" (recommended): After the first failed request, the sensor will show a yellow warning status. If the following request also fails, the sensor will show an error.
  • Set sensor to "warning" for 2 intervals, then set to "down": The sensor will only show an error status after three failed requests in a row.
  • Set sensor to "warning" for 3 intervals, then set to "down": The sensor will only show an error status after four failed requests in a row.
  • Set sensor to "warning" for 4 intervals, then set to "down": The sensor will only show an error status after five failed requests in a row.
  • Set sensor to "warning" for 5 intervals, then set to "down": The sensor will only show an error status after six failed requests in a row.

Note: Sensors that monitor via Windows Management Instrumentation (WMI) will always wait at least one scanning interval until an error is shown. It is not possible to set a WMI sensor "down" immediately, so the first option will not apply to these sensor types (all other options can apply).

Note: If a sensor has defined error limits for channels, this sensor will always be set to a Down status immediately, so no "wait" option will apply.

Schedules, Dependencies, and Maintenance Window

Note: Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted; the according settings from the parent objects will always be active. However, you can define additional settings here. They will be active in parallel to the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days, hours) throughout the week. With the period list option it is also possible to pause monitoring for a specific time span. You can create new schedules and edit existing ones in the account settings. Note: Schedules are generally inherited. New schedules will be added to existing ones, so all schedules are active.

Maintenance Window

Specify if you want to set-up a one-time maintenance window. During a maintenance window this object and all child objects will not be monitored. They will enter a paused state then. Choose between:

  • Not set (monitor continuously): No maintenance window will be set.
  • Set up a one-time maintenance window: Pause monitoring within a maintenance window.

Maintenance Begins At

This field is only visible if maintenance window is enabled above. Use the date time picker to enter the start date and time of the maintenance window.

Maintenance End At

This field is only visible if maintenance window is enabled above. Use the date time picker to enter the end date and time of the maintenance window.

Dependency Type

Define a dependency type. Dependencies can be used to pause monitoring for an object depending on the status of another. You can choose between:

  • Use parent: Pause the current sensor if the device it is created on is in a Down status, or if it is paused by another dependency.
  • Select object: Pause the current sensor if the device it is created on is in an Down status, or if it is paused by another dependency. Additionally, pause the current sensor if a specific other object in the device tree is in a Down status, or if it is paused by another dependency. Select below.
  • Master object for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of the device it is created on: If the sensor is in a Down status, the device will be paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor will be paused if the parent group of its parent device is in a Down status, or if it is paused by another dependency.

Note: Testing your dependencies is easy! Simply choose Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later all dependent objects should be paused. You can check all dependencies in your PRTG installation by selecting Devices | Dependencies from the main menu bar.

Dependency

This field is only visible if the select object option is enabled above. Click on the reading-glass symbol and use the object selector to choose an object on which the current sensor will be dependent on.

Delay (Seconds)

Define a time span. After the master object for this dependency comes back to an Up status, monitoring of the depending objects will be additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Please enter an integer value in seconds. Note: This setting is not available if you choose this sensor to be the Master object for parent. In this case, please define delays in the parent Device Settings or the superior Group Settings.

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.

Example: Number Extraction with Regular Expression

If you want to extract a number in the response string using a regular expression, please note that the index for captures in this sensor is based on 1 (not on 0). Furthermore, capturing groups are not created automatically. The example below will illustrate this issue.

Consider the following string as returned by a request for CPU usage:

 5 Sec (3.49%), 1 Min (3.555%), 5 Min (3.90%)

 

Assuming you would like to filter for the number 3.555, i.e., the percentage in the second parentheses. Then enter the following regex in the Regular Expression field:

(\d+\.\d+).*(\d+\.\d+).*(\d+\.\d+) 

 

As Index of Capturing Group enter 3. This will extract the desired number 3.555.

The index has to be 3 in this case because the capturing groups here are the following:

  • Group 1 contains "3.49%), 1 Min (3.555), 5 Min (3.90"
  • Group 2 contains "3.49"
  • Group 3 contains "3.555"
  • Group 4 contains "3.90"

Please keep in mind this note about index and capturing groups when using number extraction.

More

My WMI sensors don't work. What can I do?

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.

Notifications

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

Others

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

Sensor Settings Overview

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

Keywords: