错误1：
# systemctl status rabbitmq-server.service
● rabbitmq-server.service - RabbitMQ broker
Loaded: loaded (/usr/lib/systemd/system/rabbitmq-server.service; disabled; vendor preset: disabled)
Drop-In: /etc/systemd/system/rabbitmq-server.service.d
└─limits.conf
Active: failed (Result: exit-code) since Tue 2016-03-15 13:17:04 EDT; 34s ago
Process: 1510 ExecStop=/usr/lib/rabbitmq/bin/rabbitmqctl stop (code=exited, status=2)
Process: 1352 ExecStart=/usr/lib/rabbitmq/bin/rabbitmq-server (code=exited, status=1/FAILURE)
Main PID: 1352 (code=exited, status=1/FAILURE)
Mar 15 13:15:57 openstack_l systemd[1]: rabbitmq-server.service: Got notification message from PID 1366, but reception only permitted for main PID 1352
Mar 15 13:15:57 openstack_l systemd[1]: rabbitmq-server.service: Got notification message from PID 1367, but reception only permitted for main PID 1352
Mar 15 13:16:27 openstack_l rabbitmq-server[1352]: ERROR: epmd error for host openstack_l: timeout (timed out)
Mar 15 13:16:27 openstack_l systemd[1]: rabbitmq-server.service: main process exited, code=exited, status=1/FAILURE
Mar 15 13:16:27 openstack_l rabbitmqctl[1510]: Stopping and halting node rabbit@openstack_l ...
Mar 15 13:16:34 openstack_l rabbitmqctl[1510]: Error: unable to connect to node rabbit@openstack_l: nodedown
Mar 15 13:17:04 openstack_l systemd[1]: rabbitmq-server.service: control process exited, code=exited status=2
Mar 15 13:17:04 openstack_l systemd[1]: Failed to start RabbitMQ broker.
Mar 15 13:17:04 openstack_l systemd[1]: Unit rabbitmq-server.service entered failed state.
Mar 15 13:17:04 openstack_l systemd[1]: rabbitmq-server.service failed.