1. 安装chrony
yum install chrony -y
vim /etc/chrony.conf
修改chrony配置文件（替换默认的centos）
server ntp1.aliyun.com iburst
server ntp2.aliyun.com iburst
server ntp3.aliyun.com iburst
server ntp4.aliyun.com iburst
allow 192.168.0.0/16 #允许NTP客户同步ip段 NTP同步时需要配置 2. 启动chronyd服务，并加入开机自启
[root@localhost ~]# systemctl restart chronyd
[root@localhost ~]# systemctl enable chronyd3. 验证效果
[root@localhost ~]# timedatectl
Local time: Tue 2021-05-18 16:51:25 CST
Universal time: Tue 2021-05-18 08:51:25 UTC
RTC time: Tue 2021-05-18 08:51:25
Time zone: Asia/Shanghai (CST, +0800)
NTP enabled: yes
NTP synchronized: yes
RTC in local TZ: no
DST active: n/a出现双YES就代表同步成功
配置多台可以重复配置chronyd服务也可以配置ntpdate客户端实时同步，多台情况下建议使用ntpdata客户端
4. NTP客户端同步
安装ntpdate命令
yum install ntpdate -y
同步指定NTP服务器时间
[root@es_node1 elasticsearch-7.6.2]# timedatectl
Local time: Tue 2021-05-18 02:23:09 CST
Universal time: Mon 2021-05-17 18:23:09 UTC
RTC time: Wed 2021-06-02 07:06:48
Time zone: Asia/Shanghai (CST, +0800)
NTP enabled: n/a
NTP synchronized: no
RTC in local TZ: no
DST active: n/a
[root@es_node1 elasticsearch-7.6.2]# ntpdate 192.168.24.46
2 Jun 15:07:14 ntpdate[27888]: step time server 192.168.24.46 offset 1341819.732624 sec
[root@es_node1 elasticsearch-7.6.2]# timedatectl
Local time: Wed 2021-06-02 15:07:32 CST
Universal time: Wed 2021-06-02 07:07:32 UTC
RTC time: Wed 2021-06-02 07:07:32
Time zone: Asia/Shanghai (CST, +0800)
NTP enabled: n/a
NTP synchronized: no
RTC in local TZ: no
DST active: n/a
将NTP同步加入计划任务
*/5 * * * * /usr/sbin/ntpdate 192.168.24.46 &>/dev/null 2>&1