CentOs查看當前系統所用的時區，設置ntpd授時服務之前先調整好時區，例如集羣中提供授時服務主機IP爲192.168.3.1
[xubc@master conf]$ date -R Mon, 08 Jun 2015 19:24:39 +0800
若不是我們的時區，將時區設置爲東8區的時間
cp /usr/share/zoneinfo/Asia/Shanghai /etc/localtime Mon, 08 Jun 2015 19:24:39 +0800
修改ntpd服務配置文件vim /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. #restrict 192.168.1.0 mask 255.255.255.0 nomodify notrap restrict 192.168.3.0 mask 255.255.255.0 nomodify restrict 0.0.0.0 mask 0.0.0.0 nomodify notrap noquery notrust # Use public servers from the pool.ntp.org project. # Please consider joining the pool (http://www.pool.ntp.org/join.html). server 0.centos.pool.ntp.org iburst server 1.centos.pool.ntp.org iburst server 2.centos.pool.ntp.org iburst server 3.centos.pool.ntp.org iburst server 127.127.1.0 #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 # 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
重新啓動 service ntpd start 服務作爲集羣中提供授時服務的主機，先利用網絡時間更新好授時主機192.168.3.1的時間
ntpdate 0.cn.pool.ntp.org /sbin/hwclock -w
然後在集羣上其他主機上設置crontab服務，同步更新自己時間
crontab -e 10 16 * * * (/usr/sbin/ntpdate 192.168.3.1 && /sbin/hwclock -w) >> /var/log/ntpdate.log #每天下午16:10同步授時主機上的時間