Update Zabbix from 2.4 to 3.0

service zabbix-agent stop
service zabbix-server stop
# optional backup-------
# mysqldump -u zbuser -p zabbix > zabbix.sql
# cp /etc/zabbix/zabbix_server.conf ~/zabbix-backup-2-4-7
# cp /etc/httpd/conf.d/zabbix.conf ~/zabbix-backup-2-4-7
# cp /usr/share/doc/zabbix-* ~/zabbix-backup-2-4-7
# cp -R /usr/share/doc/zabbix-* ~/zabbix-backup-2-4-7
# -----------------------
yum update http://repo.zabbix.com/zabbix/3.0/rhel/7/x86_64/zabbix-release-3.0-1.el7.noarch.rpm
yum clean all
yum update zabbix-server-mysql zabbix-web-mysql zabbix-agent zabbix-java-gateway zabbix-web
service zabbix-agent start
service zabbix-server start