Applies To:

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sol14096: The BIG-IP system may unexpectedly reboot when the syslog-ng utility logs to a remote host
Known IssueKnown Issue

Original Publication Date: 01/07/2013
Updated Date: 11/11/2016

Known Issue

The syslog-ng utility may cause high CPU utilization, resulting in a watchdog timeout and system reboot.

This issue occurs when the following conditions are met:

  • The syslog-ng utility is configured to log to a remote syslog server.
  • The BIG-IP system is unable to communicate with the remote syslog server.

If there is a disruption in the communication with the remote syslog server, the syslog-ng utility will not attempt to re-establish the connection until the syslog-ng service is restarted.


The system may crash and traffic through the BIG-IP system may be disrupted.


As a result of this issue, you may encounter one or more of the following symptoms:

  • The syslog-ng process shows CPU utilization greater than 90 percent using the following command:

    ps aux | grep syslog-ng

    For example:

    root 6394 93.0 0.0 3308 1508 ? Ss 2012 0:02 /usr/sbin/syslog-ng -p /var/run/

  • The system may experience a watchdog timeout and reboot.
  • After the system becomes unresponsive, it displays an error message in the /var/log/ltm file that appears similar to the following example:

    warning chmand[5255]: 012a0004:4: Host CPU subsystem reset caused by *** Super I/O watchdog timeout ***



F5 Product Development has assigned ID 387640 to this issue, and has confirmed that this issue exists in the products listed in the Applies To box. For information about releases or hotfixes that resolve this issue, refer to the following table:

Type of FixFixes Introduced InRelated Articles
Release11.3.0SOL2200: Most recent versions of F5 software
Hotfix11.2.1 HF6
11.2.0 HF6
10.2.4 HF7
SOL9502: BIG-IP hotfix matrix


You can mitigate this issue by ensuring that the remote syslog server is online and restarting the syslog-ng process, by typing the following command:

bigstart restart syslog-ng

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