Question

Starting MySQL database server mysqld [fail]

Posted August 13, 2015 11.1k views
UbuntuMySQLWordPress

Since yesterday evening my sql server stopped working. I’ve noticed this when my website showed this great message “Error establishing a database connection”. So I’ve tried to restart mysql service. Unfortunately nothing works. I was looking for solutions “with” google but no luck. I even tried to restore my droplet to previous one. But this one doesn’t work either. I don’t know what should I do. I’ll be grateful for any help

1 comment
  • We are facing the same issues at our end. When this issue previously happened we found that mysql has stopped. Didn’t get the any reason why it has stopped. We start it again from console using sudo /etc/init.d/mysql start

    This has happened today again and on starting mysql we are getting fail message.

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3 answers

When you would like to fix something that is not working, you should start with reading the logs your software gives ; its all free there on your server ;)
What does your mysql log say?

  • Hello,

    I got something like that. Found in /var/log/mysql error.log

    <^>150814 14:37:36 [Note] Plugin ‘FEDERATED’ is disabled.
    150814 14:37:36 InnoDB: The InnoDB memory heap is disabled
    150814 14:37:36 InnoDB: Mutexes and rwlocks use GCC atomic builtins
    150814 14:37:36 InnoDB: Compressed tables use zlib 1.2.8
    150814 14:37:36 InnoDB: Using Linux native AIO
    150814 14:37:36 InnoDB: Initializing buffer pool, size = 128.0M
    150814 14:37:37 InnoDB: Completed initialization of buffer pool
    150814 14:37:37 InnoDB: highest supported file format is Barracuda.
    InnoDB: The log sequence number in ibdata files does not match
    InnoDB: the log sequence number in the iblogfiles!
    150814 14:37:37 InnoDB: Database was not shut down normally!
    InnoDB: Starting crash recovery.
    InnoDB: Reading tablespace information from the .ibd files…
    InnoDB: Error: trying to add tablespace 135 of name ’./adminnewone/wptermrelationships.ibd’
    InnoDB: to the tablespace memory cache, but tablespace
    InnoDB: 135 of name ’./adminmoja/wp_comments.ibd’ already exists in the tablespace
    InnoDB: memory cache!<^>

    Thanks in advance
    Wojtek

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

by Brian Boucheron
WordPress is one of the most popular open source content management systems in the world. Although it started out focused on blogging, over the years it has developed into a more flexible platform for websites in general. After almost fifteen years of development it is quite polished and robust, yet issues can still come up. If you've recently attempted to load your WordPress-powered website and instead saw a message stating "Error Establishing Database Connection", the cause is most often...