I set up my first Ubuntu Server with Ubuntu 16.04, nginx, php7.0, MariaDB, nextcloud and external DynDNS using this tutorial here: Install Nextcloud 9 on Ubuntu 16.04
Please note that since 10.1.10, MariaDB uses systemd to start the service. If you have tried MYSQLD_STARTUP_TIMEOUT and it has not worked, you are probably using this or a later version. The /etc/init.d/mysql script is no longer used, so MYSQLD_STARTUP_TIMEOUT has no effect.
You need to find your mariadb.service file. In our case, it did not contain a timeout so the MariaDB default was being used. Just add:
TimeoutStartSec = 0
In the [Service] section, and it will never time out.
It would be a good idea to create your own config file containing this so it doesn't get overwritten by later re-installs.
On ubuntu 18.04, you will fine this file in
/lib/systemd/system/mariadb.service
Put your own file in
/etc/systemd/system/mariadb.service.d
Remember to run systemctl daemon-reload after adding the timeout somewhere (and maybe check /var/log/syslog to see if the reload was successful), otherwise your time out will be ignored.