centos7不同於以往linux的操作，對於開機自啓動的調整，命令有所不同。
chkconfig --list查看非系統內置服務的自啓動狀態
[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
根據提示，要查看系統內置的服務自啓動狀態需要使用命令systemctl list-unit-files，它會列出系統所有內置服務的自啓動狀態。
所以調整ntp的自啓動需要在這裏調整。
[root@vd13crmtb01 ~]# systemctl enable ntpd.service //開機自啓動
調整之後重啓系統，可是發現ntp並沒有啓動起來
[root@vd13crmtb01 ~]# pgrep ntpd //無法查看到相關進程
[root@vd13crmtb01 ~]# systemctl status ntpd
ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled)
Active: inactive (dead) //顯示開機自啓動了，但是狀態是inactive
通過查詢發現有一個chronyd服務設置爲開機自啓動，這個服務導致ntp無法開啓自啓動
[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.
通過禁止chronyd服務開機自啓動之後再將系統重啓
[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
此時，NTP的服務已經開機自啓動了，完成！