This article applies as of PRTG 22

Low disk space on probe system

The Probe Health sensor monitors the status of a probe system. Among other parameters, this sensor also shows the free disk space on the probe system in the dedicated channel Data Storage Free.

As of PRTG 18.x.37, PRTG dynamically sets limits for this channel. If the limits are undercut, the sensor shows the following message:

Data storage is less than %s.

For versions previous to PRTG 18.x.37, this channel will show the Warning status by default if less than 5120 MB are available on the disk, and the Down status for less than 1024 MB. In this case, the sensor shows a message like the following:

2.394 Mbyte (Data Storage Free) is below the warning limit of 5.120 Mbyte. The probe system is running out of disk space. Please add additional space to the PRTG data path. For details, please see https://kb.paessler.com/en/topic/64628

Most sensors write their data to the disk on the PRTG core server system—usually, you need about 200 KB of disk space per sensor per day. There are also some sensors (for example, the Syslog Receiver sensor, the SNMP Trap Receiver sensor, or the HTTP Full Web Page sensor) that write data to the disk on the (remote) probe system. These sensors can consume a lot of available disk space on the probe system if you do not appropriately configure them.

You can check the PRTG data path to see which data takes most space. In particular, consider the following aspects on the probe system where the Probe Health sensor is showing the Warning or the Down status:

• Do you run SNMP Trap Receiver or Syslog Receiver sensors?
  
  Check the size of the corresponding database folder, Trap Database or Syslog Database. If you see very high disk usage here, consider reconfiguring these sensors in PRTG so that they store less data. For example, refine the include filters of these sensors.
• Do you run an HTTP Full Web Page sensor?
  • Do you have a huge Screenshots (Fullpage Sensor) directory? Check the Full Web Page Download Settings of this sensor. If you set the option to store screenshots of all sensor results in section Result Handling and have problems with disk space that is too low, select a different option.
  • Also check the following cache folder on the probe system where using this sensor type can result in a huge amount of used disk space, and clean it up if necessary: C:\Windows\System32\config\systemprofile\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.IE5
• Have you set appropriate data purging limits?
  
  For the HTTP Full Web Page sensor, you can set these limits in the Core & Probes settings in the PRTG web interface. The Syslog and Trap Receiver sensors have a data purging option in their sensor settings. The data purging option enables you to automatically delete old data to free up disk space. Of course, you can manually clean up the PRTG data path, but be careful that you do not delete current monitoring data or data that you still need to analyze.

If the default limits of the Probe Health sensor for the available disk space are too high for your purposes (for example, because you do not use Syslog or Trap Receiver sensors), you can manually change these limits so that you do not get a warning or error message too soon. Open the settings of the Data Storage Free channel and enter lower limits that are more convenient for your monitoring scenario into the respective Lower Warning Limit and Lower Error Limit fields. For details, see PRTG Manual: Channel Settings.