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Debugging Transaction Conflicts in Galera Cluster

If you are using Galera Cluster in multi-master mode, you will most likely run into transaction conflicts if two clients attempt to modify the same row at the same time. Such conflicts are reported a deadlock errors to the application.

Legacy applications are frequently unable to handle transaction conflicts properly and may not provide sufficient information to debug the source of the problem.

If the wsrep_log_conflicts option is set, Galera can output all the information about transaction conflicts that is available to it to the error log. As it is a dynamic option, you can enable it while the server is running, collect some entries for examination, and disable it to avoid filling up the log.

Decoding the Output

The output from wsrep_log_conflicts may look a bit intimidating at first, but in fact contains a lot of information that can be used to pin-point the offending application, module or SQL operation. The …

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Codership Webinar – Galera Cluster The Backbone of Highly Available OpenStack Database Storage – June 23rd 2015

Relational databases are ubiquitous in OpenStack: practically every OpenStack service stores its critical metadata in a database, and the MySQL family of databases is the de-facto standard for OpenStack relational data storage. The need for high availability for these relational datastores is obvious. Galera is the default multi-master strongly-consistent replication facility for highly-available relational data in OpenStack. In this webinar, we are joined by independent OpenStack expert Florian Haas to illustrate the ins and outs of Galera for OpenStack.


Speaker bio: Florian Haas is an open source software specialist, experienced technical consultant, seasoned training instructor, and frequent public speaker. He has spoken at conferences like LinuxCon, OSCON,, the OpenStack Summit, the MySQL Conference and Expo, and countless user and meetup groups across the globe.

Duration: 60 minutes

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Fast Galera Cluster Deployments in the Cloud Using Juju


The Galera Cluster Juju Charm was recently released, and it is now possible to start scalable Galera Clusters using the Juju deployment framework on the public or private cloud (OpenStack, Amazon, Azure and bare metal are all supported). All the logic required to fire up Galera is encapsulated in the Charm, which is a small package of scripts and configuration files that is automatically downloaded and added to your environment.

Installing and Configuring Juju

The Juju client is available for Ubuntu, OSX and Windows. Installing it is a matter of adding its dedicated package repository:

$ sudo add-apt-repository ppa:juju/stable
$ sudo apt-get update && sudo apt-get install juju-core

Then run

$ juju generate-config

in order to create the Juju configuration file, ~/.juju/environments.yaml, which you can then edit for your particular …

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Getting started Galera with Docker, part 1

by Erkan Yanar

Docker is an open platform for developers and sysadmins to build, ship, and run distributed applications. Consisting of Docker Engine, a portable, lightweight runtime and packaging tool, and Docker Hub, a cloud service for sharing applications and automating workflows, Docker enables apps to be quickly assembled from components and eliminates the friction between development, QA, and production environments. As a result, IT can ship faster and run the same app, unchanged, on laptops, data center VMs, and any cloud.

This is the first of a series of blog posts about using Galera with Docker. In this post, we are going to get started with Docker and Galera:

* Build a basic Docker Image (which we will extended in later posts)

* Deploy on a test cluster on a local machine

The instructions have been tested on Ubuntu 14.04 with Docker 1.5.

Build a basic Docker image

In …

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Latest Galera Cluster version supports also now MySQL 5.5. New Galera Replication Library 3.10 !

Coderhsip is pleased to announce that latest release of Galera Cluster for MySQL now supports MySQL 5.5


Downloads both MySQL 5.5 and 5.6 can be found from  We are also releasing Galera now 3.10, wsrep API version 25.

This and future releases will be available from Galera Cluster Downloads, while previous releases remain available on LaunchPad. The source repositories  and bug tracking are now on


Galera Cluster is now available as targeted packages and package repositories for a number of Linux distributions, including Ubuntu, Debian, Fedora, CentOS, OpenSUSE and SLES. Obtaining packages using a package …

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New Galera Cluster version is now released! It includes patched MySQL server 5.6.21 and Galera replication provider 3.9

Coderhsip is pleased to announce a new release of Galera Cluster for MySQL consisting of MySQL-wsrep 5.6.21 and Galera 3.9, wsrep API version 25.


This release incorporates all changes up to MySQL 5.6.21 and numerous fixes  and enhancements specific to Galera replication.


Galera Cluster is now available as targeted packages and package repositories for a number of Linux distributions, including Ubuntu, Debian, Fedora, CentOS, OpenSUSE and SLES. Obtaining packages using a package repository removes the need to download individual files and facilitates the deployment and upgrade of Galera nodes.


This and future releases will be available from, while previous releases remain available on LaunchPad. The source repositories and bug tracking are now on .



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Galera as central building block for OpenStack high availability

By Erkan Yanar 02-11-2014


OpenStack is likely the most popular open-source cloud computing platform (for IaaS or PaaS). Running OpenStack for yourself or for customers you likely want to run it without losing data and be able to scale while business grows. In this blog we are going to give a short overview to the OpenStack architecture, focusing on the Database(MySQL/MariaDB) part. Then we are going to discuss why Galera is an essential building block to achieve HA of the database and provide scaling even for very big installations.


The quite basic setup consists of:

A dashboard (program codename Horizon) providing a WebUI to manage OpenStack. Authentication is done via the identity service (Keystone). The Images service (Glance) provides images i.e. Ubuntu LTS, Centos7, etc. to start from. The Nova service starts them on a compute node. If you like to have persistent volumes you can also …

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Running a Galera Cluster for MySQL on Microsoft Azure

By Holger Kenn


A few weeks ago, I was looking into running a MySQL Galera Cluster for a customer with a large Linux IAAS deployment on Azure.

Why that? There’s ClearDB, a Microsoft Partner that offers MySQL on Azure as SaaS (Software as a service), so you can go to and pick your size. Or, if you want to run it on your own, you can pick a Ubuntu Linux Gallery image and type “apt-get install mysql-server” and that’s it, right? Well, not so fast…

ClearDB is a great offering for most customers that need a MySQL backend, but in this case, even the largest ClearDB offer was not sufficient.

So the customer followed the second path down, he created an IAAS VM (actually several VMs which each run an independent database server for different purposes) and configured his services to use these …

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Slides from past conferences

Here are my slides from past conferences. They were generated from Org Mode and Beamer. You can read more about it here.

You can get more info on the talks on their respective pages(linked).

Talk at FOSDEM 2013:

Feed me more: MySQL Memory analysed from Raghavendra Prabhu Talk at PLMCE 2013:

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Top Two Signs your MySQL Database is Maxing Out

One of the main responsibilities of any database administrator is to keep a close eye on how database performance is impacting size and storage. Decisions will have to be made on whether or not to make changes within the database structure or application itself, or to make the changes on the storage and resource side [...] Read More

Showing entries 31 to 40 of 102
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