现象：
启动nagios，20s后自动关闭，日志不报错。
Dec 1 14:05:46 rfmonitor nagios: Nagios 3.2.0 starting... (PID=4303)
Dec 1 14:05:46 rfmonitor nagios: Local time is Thu Dec 01 14:05:46 CST 2011
Dec 1 14:05:46 rfmonitor nagios: LOG VERSION: 2.0
Dec 1 14:05:46 rfmonitor nagios: ndomod: NDOMOD 1.4b8 (07-16-2009) Copyright (c) 2009 Nagios Core Development Team and Community Contributors
Dec 1 14:05:46 rfmonitor nagios: ndomod: Successfully connected to data sink. 0 queued items to flush.
Dec 1 14:05:46 rfmonitor nagios: Event broker module '/usr/local/nagios/bin/ndomod.o' initialized successfully.
Dec 1 14:05:46 rfmonitor ndo2db: Successfully connected to MySQL database
Dec 1 14:05:46 rfmonitor nagios: Finished daemonizing... (New PID=4306)
Dec 1 14:06:06 rfmonitor ndo2db: Successfully disconnected from MySQL database
分析：
因为系统已经顺利运行2年了。最近没有做配置更改，因此不应该是配置问题。
手动启动nagios
/usr/sbin/nagios /etc/nagios/nagios.cfg
报错：
File size limit exceeded
怀疑是日志满了，查找文件系统，发现host-perfdata达到文件系统限额
[root@rfmonitor ~]# ll -h /usr/local/nagios/var/host-perfdata
-rw-r--r-- 1 nagios nagios 2.0G Oct 27 17:11 /usr/local/nagios/var/host-perfdata
备份好文件，重新创建，系统恢复正常。。
