Introduction

A question frequently asked is how much latency does Galera have in geo-distributed environments. After all, snail mail can also be used for database replication, but the latency will not be acceptable.

Let’s see how Galera performs.

A Two-Datacenter Setup

We start by creating a two-node cluster using a pair of Amazon EC2 regions that are as far apart Internet-wise as it gets – Sydney and São Paulo. The underwater cable maps do not show a direct link between Australia and South America.

The ICMP round-trip time between the two regions is a steady 316 ms:

root@ip-172-31-4-77:/home/ubuntu# ping ec2-54-94-217-199.sa-east-1.compute.amazonaws.com
PING ec2-54-94-217-199.sa-east-1.compute.amazonaws.com (54.94.217.199) 56(84) bytes of data.
64 bytes from ec2-54-94-217-199.sa-east-1.compute.amazonaws.com …

Introduction

With Galera you can construct database clusters where each node is located in a different physical or even geographical location. In this blog post we will show some of the benefits from having such a geo-distributed cluster and the specific Galera features that enable practical replication across WAN links.

Benefits From Geo-Distribution

Geo-distribution allows database to break out from the single data center, which opens a whole new approach to redundancy and performance.

Increased Redundancy

Having database nodes in various geographic locations increases redundancy considerably, so that a local power failure or network outage can not possibly affect all nodes in the cluster. Outages that affect multiple availability zones within a single facility are not unheard of, but Galera allows you to go beyond the availability zones and have a truly multi-datacenter database cluster.

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Galera Cluster has the ability to add new nodes to the cluster by handling internally the transfer of the entire dataset to the new node. The same procedure, called State Snapshot Transfer (SST), applies to nodes that are rejoining the cluster after being down for a longer period of time.

A lot of operations happen during SST and there are various things that could go wrong. This article describes how to configure our server optimally for SST and how to debug any issues that arise.

The Basics

Let’s first consider all the items that play a role in the preparation and configuration of SST.

Selecting an SST Method

Galera Cluster supports several different methods for performing SST so, before adding a new node, it is worth examining the alternatives:

• rsync is the default method and requires the least amount of setup. Its disadvantage is that the donor node remains locked for all …

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 …

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, linux.conf.au, the OpenStack Summit, the MySQL Conference and Expo, and countless user and meetup groups across the globe.

Duration: 60 minutes

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Introduction

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 cloud …

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 …

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 galeracluser.com/downloads.  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 http://www.github.com/codership.

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 …

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 http://www.galeracluster.com, while previous releases remain available on LaunchPad. The source repositories and bug tracking are now on http://www.github.com/codership .

RELEASE NOTES

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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 …