PRTG Manual: SNMP Linux Disk Free Sensor

The SNMP Linux Disk Free sensor monitors the free space on disks of a Linux/Unix system via the Simple Network Management Protocol (SNMP).

SNMP Linux Disk Free Sensor

The free space that this sensor returns shows the disk space that is not yet used. Not all of this space might be available for use because a part of this space might be reserved by the system, for example, for redundancy purposes. For more information, 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.

Sensor in Other Languages

Dutch: SNMP Linux vrije schijf ruimte
French: Linux espace disponible du disque (SNMP)
German: SNMP Linux-Datenträgerspeicher
Japanese: SNMP Linux ディスクの空き容量
Portuguese: Disco livre Linux (SNMP)
Russian: Свободное пространство диска в Linux по SNMP
Simplified Chinese: SNMP Linux 磁盘可用空间
Spanish: Espacio libre en disco Linux (SNMP)

Remarks

Consider the following remarks and requirements for this sensor:

Remark	Description
IPv6	This sensor supports IPv6.
Performance impact	This sensor has a low performance impact.
Knowledge Base	Knowledge Base: Why do SSH Disk Free and SNMP Linux Disk Free show different values for my target Linux system? Knowledge Base: Monitoring Linux problem - SNMP port not reachable

Basic Sensor Settings

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

diskspacesensor
snmpdiskfreesensor

For more information about basic sensor settings, see section Sensor Settings.

Set Limits Checked for ALL Disks

In this section, you can set limits that are valid for all channels and all drives. With limits, you can define when the sensor shows the Warning or 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 in the particular channel settings. The limits are valid simultaneously, so the first limit that is breached applies.

Set Limits Checked for ALL Disks

Setting	Description
Percentage Limit Check	By default, the sensor enables percentage limits with a lower warning limit and a lower error limit. Enable or disable a limit check for the free space in percentage channels of all drives: Only use the limits in the settings of the percentage channels: Do not define sensor limits that are valid for all percentage channels. The sensor only uses the limits that 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 (default): Define sensor limits that are valid for all percentage channels. Additional fields appear below. The sensor shows the Warning or the Down status when free space limits are above or below the limits.
Upper Error Limit	This setting is only visible if you select Use the limits of both the sensor and the channel settings (default) 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
Upper Warning Limit	This setting is only visible if you select Use the limits of both the sensor and the channel settings (default) 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
Lower Warning Limit	This setting is only visible if you select Use the limits of both the sensor and the channel settings (default) 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
Lower Error Limit	This setting is only visible if you select Use the limits of both the sensor and the channel settings (default) 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you 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: Only use the limits in the settings of the byte size channels (default): Do not define sensor limits that are valid for all byte size channels. The sensor only uses limits that 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 that are valid for all byte size channels. Additional fields appear below. The sensor shows the Warning or Down status when free space limits are above or below the value. By default, byte size limits are not enabled for drives.
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 (the default unit 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
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 (the default unit 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
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 (the default unit 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
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 (the default unit 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 or leave the field empty. The limits that you set here are valid for all channels of this sensor. You can additionally set individual limits for each channel in the channel settings. Both the limits that you set here and in the channel settings are valid simultaneously.
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: Deactivate alarm (default): Do not send an alert for a removed disk. Activate alarm: Send an alert if a monitored disk is removed or not found.

Sensor Display

Setting	Description
Primary Channel	Select a channel from the list to define it as the primary channel. In the device tree, PRTG displays the last value of the primary channel below the sensor's name. The available options depend on what channels are available for this sensor. You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.
Graph Type	Define how this sensor shows different channels: 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. You 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 select Stack channels on top of each other above. Select a unit from the list. PRTG stacks all channels with this unit 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.

Setting

Description

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, PRTG displays the last value of the primary channel below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how this sensor shows different channels:

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.
You 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 select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit 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 these 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.

Channel List

Which channels the sensor actually shows might depend on the target 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.
Free Bytes [Partition]	The free space
Free INodes [Partition]	The free index nodes (%)
Free Space [Partition]	The free space (%)
Total	The free total disk space