Question

MariaDB stops after a while on ubuntu 14.04 and cannot restart

I have an $5 droplet with a LAMP stack, where I switched out mysql for MariaDB, running WordPress. It seems that after a while, MariaDB stops and I get “error establishing a database connection” page.

I have tried to restart MariaDB, but no luck:

robin@janwillemspanjer:~$ sudo service mysql restart
stop: Unknown instance:
start: Job failed to start
robin@janwillemspanjer:~$ sudo service mysqld restart
mysqld: unrecognized service

Also, it appears that the log files are completely empty. What can I do to fix this?

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Hello, all

I will recommend you to check our article on How To Debug the WordPress Error Establishing Database Connection:

https://www.digitalocean.com/community/tutorials/how-to-debug-the-wordpress-error-establishing-database-connection

This crash is most likely due to your system running out of memory. I’d suggest that you add a swap file to give yourself a bit more of a buffer. Check out this tutorial:

How To Add Swap on Ubuntu

You will most definitely need to upgrade your droplet as you’re running out of memory and your application/website needs more resources in order to continue to operate.

What you can also do is to use the MySQLTuner script.

The MySQLTuner is a script written in Perl and allows you to quickly test your MySQL configuration and it gives you suggestions for adjustments to increase performance and stability.

According to the official GitHub page, it supports 300 indicators for MySQL/MariaDB/Percona Server in this last version.

To run the script you could do the following:

  • SSH to your Droplet
  • Download the script:
wget http://mysqltuner.pl/ -O mysqltuner.pl
  • Then execute it:
perl mysqltuner.pl

The script would run multiple checks against your MySQL instance, all checks done by MySQLTuner are documented here.

Also as stated in the official documentation, it is still extremely important for you to fully understand each change you make to a MySQL database server. If you don’t understand portions of the script’s output, or if you don’t understand the recommendations, you should consult a knowledgeable DBA or system administrator that you trust.

As a good practice make sure to always test your changes on staging environments before implementing them on your production database.

On the same note, if you want to have a worry-free MySQL hosting and focus on your application, I would recommend trying out the DigitalOcean Managed Databases:

https://www.digitalocean.com/products/managed-databases-mysql/

This was mini tutorial was posted from bobbyiliev in this question in our community: https://www.digitalocean.com/community/questions/how-to-tweak-mysql-mariadb-configuration-for-increased-performance-and-stability

You can also create a simple bash script to check if MySQL is running and if not to restart it.

#!/bin/bash

# Check if MySQL is running
sudo service mysql status > /dev/null 2>&1

# Restart the MySQL service if it's not running.
if [ $? != 0 ]; then
    sudo service mysql restart
fi

Run this script every 5 minutes using a cron job like this one:

 */5 * * * * /home/user/scripts/monitor.sh > /dev/null 2>&1

Hope that this helps! Regards, Alex

While MariaDB is a little better about memory use than MySQL, both are memory hogs. The most common support issue we see is regarding running MySQL on a 512MB droplet. Since droplets do not have a swap partition by default, when the physical memory is used up and MySQL attempts to reserve more memory it will crash. Adding a swap file to your droplet will help with this considerably but upgrading to a larger droplet would help even more.

If the service will no longer start it is likely that the database itself has been corrupted due to these crashes. If you have a backup of the data, I would recommend completely removing and re-installing mariadb.

apt-get purge mariadb-server
apt-get install mariadb-server

Unlike the apt-get remove command, using purge will also delete any configuration or data files related to the package.

If the data currently in the database is not backed up you can attempt to recover it. The first step would be to review the MySQL/MariaDB log files in /var/log to see what is happening behind the scenes when the service fails to start.