Adjusting the Size of Log Files

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This article is part of the How-To series.

pfSense stores its logs in binary circular log files that never grow in size. These are known as "clog" files. The fixed size prevents the logs from filling up available storage space and eliminates the need for rotation, but the down side is that the logs wrap around once full, losing older messages in the process. These log files are held in /var/log which is in a RAM disk on NanoBSD (optional on a full install), and on the SSD/HDD for a full install by default.

Starting with pfSense 2.2, the Log File Size (Bytes) field in the Log Settings at Status > System Logs, Settings tab, allows the user to specify the amount of storage to allocate per log file.

Short Version

To change the log file sizes:

  • Navigate to Status > System Logs, Settings tab
  • Enter a new value in Log File Size (Bytes), being careful not to overfill the disk containing the logs.
  • Click Save
  • Click Reset Log Files

Details

The default size for a log file is 511488 (~500KB) which can generally hold between 2000-3000 log entries but varies by entry size. The time span covered by logs depends entirely on how much data is logged. A quiet log file could contain months or even years of information, a busy log file may only contain minutes.

Underneath the text for Log File Size (Bytes) the current and available disk space is displayed based on the current log file sizes and their location. For example:

Disk space currently used by log files: 9.8M. Remaining disk space for log files: 11G

There are approximately 20 log files affected by the size control. The value entered in Log File Size (Bytes) is for a single log file, so the actual usage will be approximately 20 times that value. As shown above, with the default value of 511488 (~500KB), the firewall uses nearly 10MB of total log space. If the size of the logs is increased to 1024000 (1MB), then nearly 20MB would be used for logs. Be certain before changing the Log File Size (Bytes) value that the disk has enough space to hold all of the log files.

The change to the log size only takes effect when log files are reset. On NanoBSD, this would be on reboot or when manually reset. On a full install, this would only happen when the logs are manually reset. Log files may be reset individually using the Clear button on the various log tabs, or by using the master Reset Log Files button on the Log Settings page.