Prerequisites
4 nodes with Ubuntu server 16.04
management-node
data-node1
data-node2
sql-node
Root privileges on the nodes.

root@ya-VirtualBox:/usr/local/mysql# mysql -u root -p
Enter password:
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
root@ya-VirtualBox:/usr/local/mysql#

systemctl stop mysql
/etc/init.d/mysql stop
cd /usr/local/mysql
./bin/mysqld_safe --user=mysql --defaults-file=/etc/my.cnf &

root@ya-VirtualBox:/home/ya# cd /usr/local/mysql
root@ya-VirtualBox:/usr/local/mysql# ./bin/mysqld_safe --user=mysql --defaults-file=/etc/my.cnf &
[2] 13988
root@ya-VirtualBox:/usr/local/mysql# 2016-11-22T23:01:13.234900Z mysqld_safe Logging to syslog.
2016-11-22T23:01:13.239342Z mysqld_safe Logging to '/var/log/mysqld.log'.
2016-11-22T23:01:13.267098Z mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
2016-11-22T23:01:13.580544Z mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
[2]-  Done                    ./bin/mysqld_safe --user=mysql --defaults-file=/etc/my.cnf
root@ya-VirtualBox:/usr/local/mysql#