How to synchronize time across a cluster?

A basic step about synchronizing time using ntp.

1. Install Ntp Server in master computer. Run following commands in master computer:

   sudo apt-get install ntp
   sudo service ntpd start
   

2. Synchronizing time in all slavery computers.
   Assume we have setup phaseless ssh to all slavery computers, and machinefile contains all slavery computers’s host names. Then, run following commands in master computer, will let all slavery computers synchronize time based on master coputer. [Password] is sudoer’s password, [Master_Server] is host name of master computer.

   cmd='echo [Password]|sudo -S ntpdate [Master_Server]'
   for line in $(cat machinefile)
   do
    ssh $line "$cmd";
    if [ "$?" -eq "0" ]; then
    echo Success:$line.
    else
    echo Erro:$line.
    fi
   done