centos7不同于以往linux的操作，对于开机自启动的调整，命令有所不同。
chkconfig --list查看非系统内置服务的自启动状态
[root@vd13crmtb01 ~]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
iprdump 0:off 1:off 2:on 3:on 4:on 5:on 6:off
iprinit 0:off 1:off 2:on 3:on 4:on 5:on 6:off
iprupdate 0:off 1:off 2:on 3:on 4:on 5:on 6:off
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:on 4:on 5:on 6:off
vmware-tools 0:off 1:off 2:on 3:on 4:on 5:on 6:off
根据提示，要查看系统内置的服务自启动状态需要使用命令systemctl list-unit-files，它会列出系统所有内置服务的自启动状态。
所以调整ntp的自启动需要在这里调整。
[root@vd13crmtb01 ~]# systemctl enable ntpd.service //开机自启动
调整之后重启系统，可是发现ntp并没有启动起来
[root@vd13crmtb01 ~]# pgrep ntpd //无法查看到相关进程
[root@vd13crmtb01 ~]# systemctl status ntpd
ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled)
Active: inactive (dead) //显示开机自启动了，但是状态是inactive
通过查询发现有一个chronyd服务设置为开机自启动，这个服务导致ntp无法开启自启动
[root@vd13crmtb01 ~]# systemctl status chronyd
chronyd.service - NTP client/server
Loaded: loaded (/usr/lib/systemd/system/chronyd.service; enabled)
Active: inactive (dead) since Tue 2014-11-11 08:28:14 CST; 1min 45s ago
Main PID: 3033 (code=exited, status=0/SUCCESS)
CGroup: /system.slice/chronyd.service
Nov 11 08:06:31 vd13crmtb01.zj.chinamobile.com systemd[1]: Starting NTP clien...
Nov 11 08:06:31 vd13crmtb01.zj.chinamobile.com chronyd[3033]: chronyd version...
Nov 11 08:06:31 vd13crmtb01.zj.chinamobile.com chronyd[3033]: Linux kernel ma...
Nov 11 08:06:31 vd13crmtb01.zj.chinamobile.com chronyd[3033]: hz=100 shift_hz...
Nov 11 08:06:31 vd13crmtb01.zj.chinamobile.com systemd[1]: Started NTP client...
Nov 11 08:28:14 vd13crmtb01.zj.chinamobile.com systemd[1]: Stopping NTP clien...
Nov 11 08:28:14 vd13crmtb01.zj.chinamobile.com systemd[1]: Stopped NTP client...
Hint: Some lines were ellipsized, use -l to show in full.
通过禁止chronyd服务开机自启动之后再将系统重启
[root@vd13crmtb01 ~]# systemctl disable chronyd.service
rm '/etc/systemd/system/multi-user.target.wants/chronyd.service'
[root@vd13crmtb01 ~]# pgrep ntpd
2981
[root@vd13crmtb01 ~]# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
10.70.213.132 10.70.91.148 3 u 21 64 1 1.252 0.029 0.000
*10.70.213.133 10.70.91.148 3 u 21 64 1 1.139 -0.191 0.000
此时，NTP的服务已经开机自启动了，完成！