H3C S5800和S6500交换机风扇反转告警
S5800加电之后出现告警提示：（设备后面板风扇指示灯橙色闪烁，前面板指示灯红色常亮）
display version #版本
H3C Comware Software, Version 7.1.045, Release 7123
Copyright (c) 2004-2017 New H3C Technologies Co., Ltd. All rights reserved.
H3C S5800-56C-EI uptime is 0 weeks, 0 days, 0 hours, 24 minutes
Last reboot reason : Cold reboot
%Jan 1 00:05:45:309 2011 H3C DEV/1/FAN_DIRECTION_NOT_PREFERRED: Fan 1 airflow direction is not preferred on slot 1, please check it.
%Jan 1 00:05:45:310 2011 H3C DEV/1/FAN_DIRECTION_NOT_PREFERRED: Fan 2 airflow direction is not preferred on slot 1, please check it.
S6500加电之后出现一样的提示（前面板指示灯红色常亮）
display version
H3C Comware Software, Version 7.1.045, Release 2432P05
Copyright (c) 2004-2017 New H3C Technologies Co., Ltd. All rights reserved.
H3C S6520-42QF-EI uptime is 0 weeks, 0 days, 0 hours, 3 minutes
Last reboot reason : Cold reboot
[H3C]%Jan 1 00:03:46:268 2011 H3C DEV/1/FAN_DIRECTION_NOT_PREFERRED: Fan 1 airflow direction is not preferred on slot 1, please check it.
%Jan 1 00:03:46:269 2011 H3C DEV/1/FAN_DIRECTION_NOT_PREFERRED: Fan 2 airflow direction is not preferred on slot 1, please check it.
display fan
Slot 1:
Fan 1:
State : FanDirectionFault
Airflow Direction: Port-to-power
Prefer Airflow Direction: Power-to-port
Fan 2:
State : FanDirectionFault
Airflow Direction: Port-to-power
Prefer Airflow Direction: Power-to-port 问题出现原因：
检查交换机风扇配置信息发现交换机风扇的实际气流方向为 Airflow Direction: Port-to-power；而配置用户下看到风扇模块的首选气流方向为：Prefer Airflow Direction: Power-to-port，两者不一致（交换机风扇反转），导致交换机风扇状态为：State : FanDirectionFault，风扇信号灯告警，交换机SYS信号灯告警。
处理方法：
因为风扇模块的实际气流方向是无法改变的，只能去改变风扇模块的首选气流方向和风扇实际气流方向一致，操作步骤如下：
display fan
Slot 1:
Fan 1:
State : FanDirectionFault #风扇方向故障
Airflow Direction: Port-to-power #实际气流方向
Prefer Airflow Direction: Power-to-port #首选气流方向
Fan 2:
State : FanDirectionFault
Airflow Direction: Port-to-power
Prefer Airflow Direction: Power-to-port 调整交换机的首选气流方向：
[H3C]fan prefer-direction slot 1 port-to-power
[H3C]display fan
Slot 1:
Fan 1:
State : Normal #状态正常
Airflow Direction: Port-to-power #实际气流方向
Prefer Airflow Direction: Port-to-power #首选气流方向
Fan 2:
State : Normal
Airflow Direction: Port-to-power
Prefer Airflow Direction: Port-to-power修改配置后，交换机各指示灯恢复正常