<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: SSH Disk Free Sensor

The SSH Disk Free sensor monitors free space on disks of a Linux/Unix system using Secure Shell (SSH).

It shows the following:

  • Free disk space in bytes for every mounted partition
  • Free disk space in percent for every mounted partition
  • Total disk space

Note: The free space returned by this sensor type shows the available disk space of the volume, minus a reserve defined for this volume (for example, for redundancy purposes). So, this sensor shows the disk space that is actually available for use. The size of the reserved disk space can be defined with tune2fs. For details, please see the More section below.

SSH Disk Free Sensor

SSH Disk Free Sensor

Click here to enlarge: http://media.paessler.com/prtg-screenshots/ssh_disk_free.png

Remarks

  • For this sensor type credentials for Linux/Solaris/Mac OS (SSH/WBEM) systems must be defined for the device you want to use the sensor on.
  • Note: This sensor type cannot support all Linux/Unix and Mac OS distributions.
  • For a general introduction to SSH monitoring, please see manual section Monitoring via SSH.

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.

Sensor Settings

On the details page of a sensor, click on the Settings tab to change its settings.

Note: Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created this sensor. See section Device Settings for details. For some sensor types, you can define the monitoring target explicitly in the sensor settings. Please see below for details about available settings.

Basic Sensor Settings

Sensor Name

Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, and in alarms, logs, notifications, reports, maps, libraries, and tickets.

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 is placed in sensor lists. Top priority is at the top of a list. You can choose from one star (low priority) to five stars (top priority).

SSH Specific

Connection Timeout (Sec.)

Define a timeout for the connection. This is the the time the sensor waits to establish a connection to the host. You should keep this value as low as possible. The maximum value is 900 seconds (15 minutes). Please enter an integer value.

Shell Timeout (Sec.)

Define a timeout for the shell response. This is the time in seconds the sensor waits for the shell to return a response after it has sent its specific command (e.g. cat /proc/loadavg). The maximum value is 60 seconds (1 minute). Please enter an integer value.

SSH Port

Define which port this sensor uses for the SSH connection. Choose between:

  • Inherit port number from parent device (default): Use the port number as defined in the Credentials for Linux/Solaris/Mac OS (SSH/WBEM) Systems section of the device this sensor is created on.
  • Enter custom port number: Do not use the port number from the parent device settings, but define a different port number below.

Use Port Number

This field is only visible if you enabled the custom port number setting above. Enter the port number (between 1 and 65535) that this sensor uses for the SSH connection. Please enter an integer value.

Result Handling

Define what PRTG will do with the result of the sensor. Choose between:

  • Discard sensor result: Do not store the sensor result.
  • Write sensor result to disk (Filename: "Result of Sensor [ID].txt"): Store the last result received from the sensor to the "Logs (Sensor)" directory (on the Master node, if in a cluster). File name: Result of Sensor [ID].txt. 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.

Set limits checked against ALL disks

In this section you can set limits that are valid for all channels and all drives. By entering limits, you can define when the sensor will enter a Warning or Down status, depending on the data provided by all drives that this sensor monitors. If you want to define limits for separate channels individually please use the limit settings in the sensor Channel settings.

Note: All limits that you define here are valid additionally to the limits defined in the particular Channels settings! The limits are valid simultaneously, so the first limit that is breached applies.

Percentage Limit Check

Enable or disable a limit check for the free space in percentage channels of all drives. By default, percentage limits are enabled with lower warning and lower error limit. Choose between:

  • Only use the limits in the settings of the percentage channels: Do not define sensor limits which are valid for all percentage channels. The sensor only uses limits which you define in the settings of the particular "free space in percent" channels to determine the status.
  • Use the limits of both the sensor and the channel settings: Define limits for the sensor which are valid for all drives (percentage channels). Additional fields appear below. The sensor enters a Warning or Down status when free space limits are undercut or overrun.

Upper Error Limit

This field is only visible if you enable percentage limit check above. Specify an upper limit in percent for a Down status. If the free disk space of one of your drives overruns this percent value, the sensor switches to Down. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Upper Warning Limit

This field is only visible if you enable percentage limit check above. Specify an upper limit in percent for a Warning status. If the free disk space of one of your drives overruns this percent value, the sensor switches to Warning. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Lower Warning Limit

This field is only visible if you enable percentage limit check above. Specify a lower limit in percent for a Warning status. If the free disk space of one of your drives undercuts this percent value, the sensor switches to warning. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Lower Error Limit

This field is only visible if you enable percentage limit check above. Specify a lower limit in percent for a Down status. If the free disk space of one of your drives undercuts this percent value, the sensor switches to Down. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Size Limit Check

Enable or disable a limit check for the free bytes channels of all drives. By default, byte size limits are not enabled for drives. Choose between:

  • Only use the limits in the settings of the byte size channels: Do not define sensor limits which are valid for all byte size channels. The sensor only uses limits which you define in the settings of the particular free space in bytes channels to determine the status.
  • Use the limits of both the sensor and the channel settings: Define limits for the sensor which are valid for all drives (byte size channels). Additional fields appear below. The sensor enters a Warning or Down status when free space limits are undercut or overrun.

Upper Error Limit

This field is only visible if you enable byte limit check above. Specify an upper limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MByte). If the free disk space of one of your drives overruns this bytes value, the sensor switches to Down. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Upper Warning Limit

This field is only visible if you enable byte limit check above. Specify an upper limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MByte). If the free disk space of one of your drives overruns this bytes value, the sensor switches to Warning. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Lower Warning Limit

This field is only visible if you enable byte limit check above. Specify a lower limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MByte). If the free disk space of one of your drives undercuts this bytes value, the sensor switches to Warning. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Lower Error Limit

This field is only visible if you enable byte limit check above. Specify a lower limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MByte). If the free disk space of one of your drives undercuts this bytes value, the sensor switches to Down. Please enter an integer value or leave the field empty.

Note: The limits set here are valid for all channels of this sensor. You can additionally set individual limits for each sensor channel in the Sensor Channels Settings. The limits set here and in the channel settings are valid simultaneously!

Alarm on Missing/Removed Disk

If a monitored disk is removed or not found, values are set to zero. Select the alarming approach in this case. Choose between:

  • Deactivate alarm (default): Select this option if you do not want an alarm for a removed disk.
  • Activate alarm: Select this option if you want to be alerted if a monitored disk is removed.

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

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

When a Sensor Reports an Error

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": Show an error status only after three failed requests in a row.
  • Set sensor to "warning" for 3 intervals, then set to "down": Show an error status only after four failed requests in a row.
  • Set sensor to "warning" for 4 intervals, then set to "down": Show an error status only after five failed requests in a row.
  • Set sensor to "warning" for 5 intervals, then set to "down": Show an error status only after six failed requests in a row.

Note: Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval until they show an error. 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.

Note: If a channel uses lookup values, the sensor will always be set to a Down status immediately, so no "wait" options 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. You can define a time span for a monitoring pause below and change it even for a running maintenance window.

Note: To terminate a current maintenance window before the defined end date, you can change the time in Maintenance End At field to a date in the past.

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.

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.

More

Knowledge Base: How and Where Does PRTG Store its Data?

Knowledge Base: Why do SSH Disk Free and SNMP Linux Disk Free show different values for my target Linux system?

Edit Sensor Channels

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

Notifications

Click 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:

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