ntp time server

搭建时钟同步服务器

这里选择 cdh1 节点为时钟同步服务器,其他节点为客户端同步时间到该节点。安装ntp:

$ yum install ntp

修改 cdh1 上的配置文件 /etc/ntp.conf :

restrict default ignore   //默认不允许修改或者查询ntp,并且不接收特殊封包
restrict 127.0.0.1        //给于本机所有权限
restrict 192.168.56.0 mask 255.255.255.0 notrap nomodify  //给于局域网机的机器有同步时间的权限
server  192.168.56.121     # local clock
driftfile /var/lib/ntp/drift
fudge   127.127.1.0 stratum 10

启动 ntp:

#设置开机启动
$ chkconfig ntpd on

$ service ntpd start

ntpq用来监视ntpd操作,使用标准的NTP模式6控制消息模式,并与NTP服务器通信。

ntpq -p 查询网络中的NTP服务器,同时显示客户端和每个服务器的关系。

$ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*LOCAL(1)        .LOCL.           5 l    6   64    1    0.000    0.000   0.000
  • ”* “:响应的NTP服务器和最精确的服务器。
  • ”+”:响应这个查询请求的NTP服务器。
  • “blank(空格)”:没有响应的NTP服务器。
  • “remote” :响应这个请求的NTP服务器的名称。
  • “refid “:NTP服务器使用的更高一级服务器的名称。
  • “st”:正在响应请求的NTP服务器的级别。
  • “when”:上一次成功请求之后到现在的秒数。
  • “poll”:当前的请求的时钟间隔的秒数。
  • “offset”:主机通过NTP时钟同步与所同步时间源的时间偏移量,单位为毫秒(ms)。

客户端的配置

在cdh2和cdh3节点上执行下面操作:

$ ntpdate cdh1

Ntpd启动的时候通常需要一段时间大概5分钟进行时间同步,所以在ntpd刚刚启动的时候还不能正常提供时钟服务,报错”no server suitable for synchronization found”。启动时候需要等待5分钟。

如果想定时进行时间校准,可以使用crond服务来定时执行。

# 每天 1:00 Linux 系统就会自动的进行网络时间校准
00 1 * * * root /usr/sbin/ntpdate 192.168.56.121 >> /root/ntpdate.log 2>&1

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