Hello, @csselo

Looking at the provided output from the error_log it seems like the droplet/server is running out of memory:

2020-03-11T15:35:39.811599Z 0 [ERROR] InnoDB: Cannot allocate memory for the buffer pool

You can check if you’ve assigned a value that is too high (compared to the droplet’s total RAM/memory). You can check the available free memory with this command:

free -m

You can check the value of buffer pool size in /etc/my.cnf less than amount of free RAM:

cat /etc/my.cnf

innodb_buffer_pool_size=100M

Once you’ve set the value of the innodbbufferpool_size to be less than the available RAM on the droplet you can restart the mysql service:

systemctl restart mysql

Hope this helps!

Regards,
Alex

Hello, @csselo

You will need to sort out the memory usage in order to resolve the problem with the MySQL service. As already mentioned you can monitor the server/droplet’s performance using top / htop and see the available free memory with free -m

You can check if the web server is busy handling requests and thus causing the memory exhaustion or if any other process is consuming the memory.

You can consider a memory upgrade as well, but I’ll suggest that you should check everything else before going for a memory upgrade.

Let me know how it goes.

Regards,
Alex

Hello, @csselo

I’d suggest that you add a swap file to give yourself a bit more of a buffer. Check out this tutorial:

https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-20-04

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