1、三個節點時間同步，cdh1,cdh2,cdh3
2、做法：cdh1從網絡時間同步，然后cdh2和cdh3從cdh1節點同步
3、安裝與自啟動設置
yum install ntp
按上面的安裝方式在內網每台節點上都安裝好NTP軟件包
完成后，都需要配置NTP服務為自啟動
chkconfig ntpd on
chkconfig --list ntpd
ntpd 0:關閉 1:關閉 2:啟用 3:啟用 4:啟用 5:啟用 6:關閉
如果2,3,4,5都為啟動，則正常。
在配置前，先使用ntpdate手動同步下時間，免得本機與外部時間服務器時間差距太大，讓ntpd不能正常同步。
ntpdate -u cn.ntp.org.cn
4、配置cdh1的/etc/ntp.conf
# For more information about this file, see the man pages # ntp.conf(5), ntp_acc(5), ntp_auth(5), ntp_clock(5), ntp_misc(5), ntp_mon(5). driftfile /var/lib/ntp/drift # Permit time synchronization with our time source, but do not # permit the source to query or modify the service on this system. restrict default kod nomodify notrap nopeer noquery restrict -6 default kod nomodify notrap nopeer noquery # Permit all access over the loopback interface. This could # be tightened as well, but to do so would effect some of # the administrative functions. restrict 127.0.0.1 restrict -6 ::1 # Hosts on local network are less restricted. # 允許內網其他機器同步時間 restrict 192.168.189.0 mask 255.255.255.0 nomodify notrap # Use public servers from the pool.ntp.org project. # Please consider joining the pool (http://www.pool.ntp.org/join.html). server cn.ntp.org.cn perfer #broadcast 192.168.1.255 autokey # broadcast server #broadcastclient # broadcast client #broadcast 224.0.1.1 autokey # multicast server #multicastclient 224.0.1.1 # multicast client #manycastserver 239.255.254.254 # manycast server #manycastclient 239.255.254.254 autokey # manycast client # 允許上層時間服務器主動修改本機時間 restrict cn.ntp.org.cn nomodify notrap noquery # 外部時間服務器不可用時，以本地時間作為時間服務 server 127.127.1.0 # local clock fudge 127.127.1.0 stratum 10 # Enable public key cryptography. #crypto includefile /etc/ntp/crypto/pw # Key file containing the keys and key identifiers used when operating # with symmetric key cryptography. keys /etc/ntp/keys # Specify the key identifiers which are trusted. #trustedkey 4 8 42 # Specify the key identifier to use with the ntpdc utility. #requestkey 8 # Specify the key identifier to use with the ntpq utility. #controlkey 8 # Enable writing of statistics records. #statistics clockstats cryptostats loopstats peerstats
5、啟動ntp服務
service ntpd start
啟動后，一般需要5-10分鍾左右的時候才能與外部時間服務器開始同步時間。
6、通過watch ntpq -p 查看網絡ntp服務器
7、然后去cdh2和cdh3去修改/ect/ntp.conf,向cdh1同步時間
修改一行：server cdh1
8、分別在cdh2和cdh3啟動ntp
service ntpd start
9、其他命令
service ntpd restart 重啟ntp
service ntpd stop 停止ntp
ntpstat 命令查看時間同步狀態，這個一般需要5-10分鍾后才能成功連接和同步
[root@cdh2 opt]# ntpstat
synchronised to NTP server (192.168.189.128) at stratum 4
time correct to within 48 ms
polling server every 64 s