The system log /var/log/messages are getting trimmed or deleted automatically, and the old log will not be rotated to messages.1, messages.2, or so.
The system log will be rotated by the logrotate, a cron job scheduled daily. This problem is due to an incorrect logrotate configuration. Checking the logrotate configuration file /etc/logrotate.conf below:
# rotate log files weekly #weekly # keep 40 weeks worth of backlogs #rotate 40
the rotation interval/times are all commented out. With this setting, the system log is trimmed without rotation.
In order to avoid this, modify the /etc/logrotate.conf and specify a proper rotation interval. For example, the configuration below:
weekly rotate 4
This will rotate the logs weekly, and log files will be rotated four times before being overwritten. For more information on logrotate, check the man page:
# man logrotate