上一篇介绍了centos7新增五大特性，这篇记安装遇到过的坑...
现在安装centos7类似用大白菜安装系统，有系统工具分区加密数据。
选配安装类型，如最小安装，web服务器安装等。网络选项最好是先开启，要不，装好系统好后，ifcfg-enp3s0 适别不了，以前centos6都是ifcfg-eth0， 出现network重启失败，如下：
RHEL7/CentOS7安装完成并配置好所有网络相关配置后重启机器，使用systemctl --failed检查是否有失败的服务，发现在network服务启动失败，使用systemctl status network查看服务状态，得到如下错误信息：
1. <span style="font-family:Microsoft YaHei;font-size:14px;"># systemctl status network
2. network.service - LSB: Bring up/down networking
3. Loaded: loaded (/etc/rc.d/init.d/network)
4. Active: failed (Result: exit-code) since Sun 2014-11-23 22:09:08 EST; 15min ago
5. Process: 597 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)
6.
7. Nov 23 22:09:07 hdcoe02 network[597]: Bringing up loopback interface: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
8. Nov 23 22:09:07 hdcoe02 network[597]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
9. Nov 23 22:09:08 hdcoe02 network[597]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
10. Nov 23 22:09:08 hdcoe02 network[597]: Could not load file '/etc/sysconfig/network-scripts/ifcfg-lo'
11. Nov 23 22:09:08 hdcoe02 network[597]: [ OK ]
12. Nov 23 22:09:08 hdcoe02 network[597]: Bringing up interface enp0s25: Error: Connection activation failed: Connection 'enp0s25' is not available on the device enp0s25 at this time.
13. Nov 23 22:09:08 hdcoe02 network[597]: [FAILED]
14. Nov 23 22:09:08 hdcoe02 systemd[1]: network.service: control process exited, code=exited status=1
15. Nov 23 22:09:08 hdcoe02 systemd[1]: Failed to start LSB: Bring up/down networking.
16. Nov 23 22:09:08 hdcoe02 systemd[1]: Unit network.service entered failed state.</span>
通过查找相关文档，使用如下方法解决了问题：设定开机启动一个名为NetworkManager-wait-online服务，命令为：
systemctl enable NetworkManager-wait-online.service
我试了上面方法，有的机器可以，有的不行。后来干脆重装，把网络项勾上。
本期重装linux，重要是为测试docker
