PRTG Manual: SSH Disk Free Sensor
The SSH Disk Free sensor monitors the free space on disks of a Linux/Unix system using Secure Shell (SSH).
The free space that this sensor returns 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, see the Knowledge Base: Why do SSH Disk Free and SNMP Linux Disk Free show different values for my target Linux system?
For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.
- Dutch: SSH Disk vrij
- French: Espace disponible du disque (SSH)
- German: SSH Laufwerkskapazität
- Japanese: SSH ディスク空き容量
- Portuguese: Disco livre (SSH)
- Russian: Свободное пространство диска по SSH
- Simplified Chinese: SSH 磁盘可用空间
- Spanish: Espacio libre en disco (SSH)
- This sensor requires credentials for Linux/Solaris/macOS (SSH/WBEM) systems in the settings of the parent device.
- This sensor cannot support all Linux/Unix and macOS distributions.
- This sensor has a medium performance impact.
- This sensor only supports the IPv4 protocol.
- See the Knowledge Base: SSH and SFTP sensors in Unknown status
The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.
The settings that you select in the Add Sensor dialog are valid for all sensors that you create when you finish the dialog.
SSH Disk Free
Setting |
Description |
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Disk |
Select the disks that you want to monitor. PRTG creates two channels for each disk that you select.
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Click the Settings tab of a sensor to change its settings.
Setting |
Description |
---|---|
Sensor Name |
Enter a name to identify the sensor. |
Parent Tags |
Shows tags that the sensor inherits from its parent device, parent group, and parent probe.
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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.
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
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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 ( |
Usually, a sensor connects to the IP Address/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.
Setting |
Description |
---|---|
Connection Timeout (Sec.) |
Define a timeout in seconds for the connection. This is the time that the sensor waits to establish a connection to the host. Keep this value as low as possible. Enter an integer value. The maximum timeout value is 900 seconds (15 minutes).
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Shell Timeout (Sec.) |
Define a timeout in seconds 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 (for example, cat /proc/loadavg). The maximum value is 300 seconds (5 minutes). Enter an integer value.
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SSH Port |
Define which port this sensor uses for the SSH connection:
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Use Port Number |
This setting is only visible if you select Enter custom port number above. Enter the port number (between 1 and 65535) that this sensor uses for the SSH connection. Enter an integer value. |
SSH Engine |
Select the method that you want to use to access data with this SSH sensor. We strongly recommend that you use the default engine. You can still use the legacy mode for some time to ensure compatibility with your target systems. Choose between:
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Result Handling |
Define what PRTG does with the sensor result:
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Set Limits Checkes for 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 shows the Warning or the Down status, depending on the data provided by all drives that this sensor monitors. If you want to individually define limits for separate channels, use the limit settings in the channel settings.
All limits that you define here are valid in addition to the limits defined in the particular Channel settings. The limits are valid simultaneously, so the first limit that is breached applies.
Setting |
Description |
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Percentage Limit Check |
Enable or disable a limit check for the free space in percentage channels of all drives. By default, the sensor enables percentage limits with a lower warning limit and a lower error limit. Choose between:
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Upper Error Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify an upper limit in percent for the Down status. If the free disk space of one of your drives exceeds this value, the sensor changes to the Down status. Enter an integer value or leave the field empty.
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Upper Warning Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify an upper limit in percent for the Warning status. If the free disk space of one of your drives exceeds this value, the sensor changes to the Warning status. Enter an integer value or leave the field empty.
|
Lower Warning Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify a lower limit in percent for the Warning status. If the free disk space of one of your drives falls below this value, the sensor changes to the Warning status. Enter an integer value or leave the field empty.
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Lower Error Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify a lower limit in percent for the Down status. If the free disk space of one of your drives falls below this value, the sensor changes to the Down status. Enter an integer value or leave the field empty.
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Size Limit Check |
Enable or disable a limit check for the free bytes channels of all drives:
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Upper Error Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify an upper limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MB). If the free disk space of one of your drives exceeds this value, the sensor changes to the Down status. Enter an integer value or leave the field empty.
|
Upper Warning Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify an upper limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MB). If the free disk space of one of your drives exceeds this value, the sensor changes to the Warning status. Enter an integer value or leave the field empty.
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Lower Warning Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify a lower limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MB). If the free disk space of one of your drives falls below this value, the sensor changes to the Warning status. Enter an integer value or leave the field empty.
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Lower Error Limit |
This setting is only visible if you select Use the limits of both the sensor and the channel settings above. Specify a lower limit. Use the same unit as shown by the free bytes channels of this sensor (by default this is MB). If the free disk space of one of your drives falls below this value, the sensor changes to the Down status. Enter an integer value or leave the field empty.
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Alarm on Missing/Removed Disk |
If a monitored disk is removed or not found, the sensor sets the values to zero. Select the alarm approach in this case:
|
Setting |
Description |
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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.
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Graph Type |
Define how different channels are shown for this sensor:
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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. |
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 under the corresponding setting name to disable the inheritance and to display its options.
For more information, see section Inheritance of Settings.
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:
|
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:
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Schedules, Dependencies, and Maintenance Window
You cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.
Setting |
Description |
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Schedule |
Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:
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Maintenance Window |
Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:
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Maintenance Begins |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the one-time maintenance window. |
Maintenance Ends |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the one-time maintenance window. |
Dependency Type |
Select a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:
|
Dependency |
This setting is only visible if you enable Select a sensor above. Click |
Dependency Delay (Sec.) |
This setting is only visible if you select Select a sensor above. Define a time span in seconds for the dependency delay. After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. Enter an integer value.
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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:
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Click to interrupt the inheritance.
Which 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.
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, you can inherit these settings to all sensors underneath. You can set units for the following channel types (if available):
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Which channels the sensor actually shows might depend on the monitored device, the available components, and the sensor setup.
Channel |
Description |
---|---|
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. |
Free Bytes [Mounted Partition] |
The free space in bytes |
Free Space [Mounted Partition] |
The free space in percent |
Total |
The total space in bytes |
Knowledge Base
Why do SSH Disk Free and SNMP Linux Disk Free show different values for my target Linux system?
SSH and SFTP sensors in Unknown status
What security features does PRTG include?
How do I set up SSH sensors with my AWS Linux instances?
For more information about sensor settings, see the following sections: