Monitoring your system : Logging : About logs & logging : Log severity levels
 
Log severity levels
Each log message contains a Severity (pri) field that indicates the severity of the event that caused the log message, such as pri=warning.
Table 9: Log severity levels
Level
(0 is greatest)
Name
Description
0
Emergency
The system has become unusable.
1
Alert
Immediate action is required.
2
Critical
Functionality is affected.
3
Error
An error condition exists and functionality could be affected.
4
Warning
Functionality could be affected.
5
Notification
Information about normal events.
6
Information
General information about system operations.
For each location where the FortiADC appliance can store log files (disk, memory, Syslog or FortiAnalyzer), you can define a severity threshold. The FortiADC appliance will store all log messages equal to or exceeding the log severity level you select.
For example, if you select Error, the FortiADC appliance will store log messages whose log severity level is Error, Critical, Alert, and Emergency.
 
Avoid recording log messages using low log severity thresholds such as information or notification to the local hard disk for an extended period of time. A low log severity threshold is one possible cause of frequent logging. Excessive logging frequency can cause undue wear on the hard disk and may cause premature failure.
For more information, see “Logging to a FortiAnalyzer or Syslog server”.