Linux 集群时间同步(Ubuntu)

在配置hadoop集群时，时间同步是必须要做的，否则会出现各种意想不到的问题。

hadoop102 为 ntp server，hadoop103以及hadoop104 为ntp client（即需要同步时间机器）

1.全部机器都要安装ntp以及ntpdate

sudo apt-get install ntp

sudo apt-get install ntpdate

2.关闭所有的机器的ntp,每个机器执行命令 一下命令

sudo service ntp stop

查看ntp状态

sudo service ntp status

3.修改ntp server即hadoop102的/etc/ntp.conf文件

sudo vim /etc/ntp.conf

相关条文解释，参考https://www.cnblogs.com/xwdreamer/p/3448773.html

# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
  
driftfile /var/lib/ntp/ntp.drift

# Leap seconds definition provided by tzdata
leapfile /usr/share/zoneinfo/leap-seconds.list

# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable

# Specify one or more NTP servers.

# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
pool 0.ubuntu.pool.ntp.org iburst
pool 1.ubuntu.pool.ntp.org iburst
pool 2.ubuntu.pool.ntp.org iburst
pool 3.ubuntu.pool.ntp.org iburst

# Use Ubuntu‘s ntp server as a fallback.
pool ntp.ubuntu.com

# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details.  The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don‘t allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery limited
restrict -6 default kod notrap nomodify nopeer noquery limited

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1

# Needed for adding pool entries
restrict source notrap nomodify noquery

# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
#restrict 192.168.123.0 mask 255.255.255.0 notrust


# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255

# If you want to listen to time broadcasts on your local subnet, de-comment the
# next lines.  Please do this only if you trust everybody on the network!
#disable auth
#broadcastclient

改为如下后保存：

# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
  
driftfile /var/lib/ntp/ntp.drift

# Leap seconds definition provided by tzdata
leapfile /usr/share/zoneinfo/leap-seconds.list

# Enable this if you want statistics to be logged.
#statsdir /var/log/ntpstats/

statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
#pool 0.ubuntu.pool.ntp.org iburst
#pool 1.ubuntu.pool.ntp.org iburst
#pool 2.ubuntu.pool.ntp.org iburst
#pool 3.ubuntu.pool.ntp.org iburst

# Use Ubuntu‘s ntp server as a fallback.
#pool ntp.ubuntu.com
server 127.127.1.0
fudge 127.127.1.0 stratum 10


# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details.  The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
#
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.

# By default, exchange time with everybody, but don‘t allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery limited
restrict -6 default kod notrap nomodify nopeer noquery limited

# Local users may interrogate the ntp server more closely.
restrict 127.0.0.1
restrict ::1

# Needed for adding pool entries
restrict source notrap nomodify noquery

# Clients from this (example!) subnet have unlimited access, but only if
# cryptographically authenticated.
restrict 192.168.123.0 mask 255.255.255.0 nomodify notrap


# If you want to provide time to your local subnet, change the next line.
# (Again, the address is an example only.)
#broadcast 192.168.123.255

4.对ntp server （hadoop102）执行命令，开启服务

sudo service ntp start

5.同步时间(除hadoop102的其他机器都要执行)

sudo ntpdate hadoop102

6 在除hadoop102的其他机器，将同步时间的命令放在crontab中(切换到root用户下操作)

*/10 * * * * /usr/sbin/ntpdate hadoop102

每十分钟更新一次

相关错误：

 no server suitable for synchronization found

http://www.blogjava.net/spray/archive/2008/07/10/213964.html

Ubuntu 时间设置

https://www.cnblogs.com/qiumingcheng/p/12210629.html