1. Cluster time synchronization
Find a machine, as a practical server, all machines will synchronize with the cluster time regularly, for example, synchronize the time every ten minutes.
1.1 Steps
1.1.1 Time server configuration
[[email protected] hadoop-2.7. 7]$ rpm -qa | grep ntp
ntp-4.2.6p5-28.el7.centos.x86_64
ntpdate-4.2.6p5-28.el7.centos.x86_64
[[email protected] hadoop-2.7.7 ]$ vim /etc/ntp.conf
#Authorization 172.16.0.0/All machines in the 16 network segment can query the time from this machine
restrict 172.16.0.0 mask 255.255.0.0 nomodify notrap
#The cluster is in the local area network and does not use his time on the Internet
server 0.centos.pool.ntp.org iburst
#When the node loses network connection, the local time can still be used as a time server to provide time synchronization for other nodes in the cluster
server 127.127.1.0
fudge 127.127.1.0 stratum 10
1.1.2 Modify /etc/sysconfig/ntpd file
[ [email protected] hadoop-2.7.7]$ vim /etc/sysconfig/< span style="color: #000000;">ntpd
#Add the following content to synchronize the hardware time with the system time
SYNC_HWCLOCK=yes
1.1.3 Restart ntpd service
[[emailprotected] hadoop -2.7.7]$ systemctl enable ntpd
[[email protected] hadoop-2.7.7 ]$ systemctl restart ntpd
1.1.4 Other machine configuration
[[emailprotected] hadoop-2.7.7]$ crontab -e
*/10 * * * * /usr/sbin/ntpdate hadoop01
#Modify any time at will, wait for 10 minutes to see if it is synchronized with the practice of hadoop01 machine
[[email protected] hadoop-2.7.7 ]$ date -s " 2019-8-4 11:27:30"
[[email protected] hadoop-2.7.7 ]$ date
[[email protected] hadoop-2.7.7 ]$
[[email protected] hadoop-2.7.7]$ rpm -qa | grep ntp
ntp-4.2.6p5-28.el7.centos.x86_64
ntpdate-4.2.6p5-28.el7.centos.x86_64
[[email protected] hadoop-2.7.7 ]$ vim /etc/ntp.conf
#Authorization 172.16.0.0/All machines in the 16 network segment can query the time from this machine
restrict 172.16.0.0 mask 255.255.0.0 nomodify notrap
#The cluster is in the local area network and does not use his time on the Internet
server 0.centos.pool.ntp.org iburst
#When the node loses network connection, the local time can still be used as a time server to provide time synchronization for other nodes in the cluster
server 127.127.1.0
fudge 127.127.1.0 stratum 10
[[email protected] hadoop-2.7 .7]$ vim /etc/sysconfig/ntpd
#Add the following content to synchronize the hardware time with the system time
SYNC_HWCLOCK=yes
[[email protected] hadoop-2.7. 7]$ systemctl enable ntpd
[[email protected] hadoop-2.7.7 ]$ systemctl restart ntpd
[[email protected] hadoop-2.7.7]$ crontab -e
*/10 * * * * /usr/sbin/ntpdate hadoop01
#Modify any time at will, wait for 10 minutes to see if it is synchronized with the practice of hadoop01 machine
[[email protected] hadoop-2.7.7 ]$ date -s " 2019-8-4 11:27:30"
[[email protected] hadoop-2.7.7 ]$ date
[[email protected] hadoop-2.7.7 ]$