在将heartbeat应用到生产环境中，还是有许多要注意的地方，一不小心就可能导致heartbeat无法切换或脑裂的情况，下面来介绍下由于iptables导致脑裂的现象。
主:192.168.3.218
192.168.4.218 心跳ip
usvr-218 主机名
备:192.168.3.128
192.168.4.128 心跳ip
usvr-128 主机名
现象：当启动heartbeat主后，VIP在218上生效；然后再启动heartbeat备，VIP在128上也生效；此时脑裂产生，导致访问异常。
解决思路：
1.查看主机和备机的日志
主机218日志如下（只列出部分日志）：
heartbeat[27330]: 2015/01/27_09:05:29 ERROR: Message hist queue is filling up (500 messages in queue)
heartbeat[27330]: 2015/01/27_09:05:30 ERROR: Message hist queue is filling up (500 messages in queue)
heartbeat[27330]: 2015/01/27_09:05:30 ERROR: Message hist queue is filling up (500 messages in queue)
heartbeat[27330]: 2015/01/27_09:05:31 ERROR: Message hist queue is filling up (500 messages in queue)
heartbeat[27330]: 2015/01/27_09:05:32 ERROR: Message hist queue is filling up (500 messages in queue)
heartbeat[27330]: 2015/01/27_09:05:32 ERROR: Message hist queue is filling up (500 messages in queue)
heartbeat[27330]: 2015/01/27_09:05:33 WARN: node usvr-128: is dead
heartbeat[27330]: 2015/01/27_09:05:33 info: Cancelling pending standby operation
heartbeat[27330]: 2015/01/27_09:05:33 info: Dead node usvr-128 gave up resources.
heartbeat[27330]: 2015/01/27_09:05:33 info: all clients are now resumed
heartbeat[27330]: 2015/01/27_09:05:33 ERROR: lowseq cannnot be greater than ackseq
heartbeat[27330]: 2015/01/27_09:05:33 info: hist->ackseq =74575, old_ackseq=0
heartbeat[27330]: 2015/01/27_09:05:33 info: hist->lowseq =74576, hist->hiseq=74824, send_cluster_msg_level=1
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Emergency Shutdown: Master Control process died.
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Killing pid 27330 with SIGTERM
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Killing pid 27334 with SIGTERM
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Killing pid 27335 with SIGTERM
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Killing pid 27336 with SIGTERM
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Killing pid 27337 with SIGTERM
heartbeat[27333]: 2015/01/27_09:05:34 CRIT: Emergency Shutdown(MCP dead): Killing ourselves.
备机128日志如下（只列出部分日志）：
Jan 27 10:11:35 heartbeat: [15999]: info: glib: ucast: bound receive socket to device: eth0
Jan 27 10:11:35 heartbeat: [15999]: info: glib: ucast: set SO_REUSEPORT(w)
Jan 27 10:11:35 heartbeat: [15999]: info: glib: ucast: started on port 694 interface eth0 to 192.168.4.218
Jan 27 10:11:35 heartbeat: [15999]: info: glib: ping heartbeat started.
Jan 27 10:11:35 heartbeat: [15999]: info: G_main_add_TriggerHandler: Added signal manual handler
Jan 27 10:11:35 heartbeat: [15999]: info: G_main_add_TriggerHandler: Added signal manual handler
Jan 27 10:11:35 heartbeat: [15999]: info: G_main_add_SignalHandler: Added signal handler for signal 17
Jan 27 10:11:35 heartbeat: [15999]: info: Local status now set to: 'up'
Jan 27 10:11:35 heartbeat: [15999]: info: Link 192.168.3.1:192.168.3.1 up.
Jan 27 10:11:35 heartbeat: [15999]: info: Status update for node 192.168.3.1: status ping
Jan 27 10:13:35 heartbeat: [15999]: WARN: node usvr-218: is dead
Jan 27 10:13:35 heartbeat: [15999]: info: Comm_now_up(): updating status to active
Jan 27 10:13:35 heartbeat: [15999]: info: Local status now set to: 'active'
Jan 27 10:13:35 heartbeat: [15999]: info: Starting child client "/usr/lib64/heartbeat/ipfail" (498,498)
Jan 27 10:13:35 heartbeat: [15999]: WARN: No STONITH device configured.
Jan 27 10:13:35 heartbeat: [15999]: WARN: Shared disks are not protected.
Jan 27 10:13:35 heartbeat: [15999]: info: Resources being acquired from localsv218.
正如如上显示，主备双方都检查对方的node死掉，从而接管VIP，导致脑裂产生。
2.初步断定是由于主备双方无法通讯或网络延迟导致，难道由于时间不同步导致，虽然时间不同不对heartbeat影响较小，但是相差很多，肯定会有问题，于是双方对时。
/usr/sbin/ntpdate ntp.api.bz&&hwclock -w
echo "0 23 * * * root /usr/sbin/ntpdate ntp.api.bz&&hwclock -w > /dev/null 2>&1" >>/etc/crontab
3.对时完毕，仍然报日志中的错误，再次检查主备配置文件，发现都没有问题，唯一区别在于主备上都有防火墙，由于heartbeat设置的是由udp 694端口通讯，于是将udp 694
端口在放火墙中放过。
在主218上加入：
/sbin/iptables -A INPUT -i eth0 -p udp -s 192.168.4.128 --dport 694 -m comment --comment "heartbeat-slave" -j ACCEPT
在备128上加入：
/sbin/iptables -A INPUT -i eth0 -p udp -s 192.168.4.218 --dport 694 -m comment --comment "heartbeat-master" -j ACCEPT
注意：1.如果防火墙策略严格时，要对心跳ip放过，否则udp通讯仍会失败
2.入口网卡针对对心跳ip的网卡
经过防火墙配置后，主备可以正常通讯了，正常情况下主节点接管VIP工作，当主节点down掉或主节点的heartbeat服务停掉，备用节点便会接管VIP
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