The latest from the MySQL community

January 23, 2014 By Severalnines

Thanks to everyone who attended this week’s webinar; if you missed the sessions or would like to watch the webinar again and browse through the slides, they are now available online.

Special thanks to Seppo Jaakola from Codership, the creators of Galera Cluster, for walking us through the various scenarios of Galera recovery. 

Webinar topics discussed: 

• Redundancy models for Galera, NDB and MongoDB / TokuMX
• Failover & Recovery (Automatic vs Manual)
• Zooming into Galera recovery procedures
• Split brains in multi-datacenter setups

Watch the replay:

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I confess I am a Galera fanboy. This post is going to present two slogans about Galera reminding you about Galera “limitations”. This is for the sake of user experience:)

Galera Phrases:

• One Cluster
• Replication

One Cluster

Think about Galera as One Cluster. As every transaction is committed virtually synchronously, the slowest node determines the (DML) speed of the cluster. This is true regarding the network too.

Replication

• Galera is still some kind of replication. So keep in mind to provide PK as for (ROW based) Replication. There is a Featurerequest of mine to have a PK option to enforce creating of Tables with a PK. Please vote for it:)

• With traditional MySQL Replication the slave might lag. This is …

January 20, 2014 By Severalnines

Alfresco is a popular collaboration tool available on the open-source market. It is Java based, and has a content repository, web application framework and web content management system. For critical large-scale implementations that require 24*7 uptime, a multi-node cluster would be appropriate. Since Alfresco depends on external components such as the database and the filesystem, clustering the Alfresco instances only would not be enough.

In this post, we are going to show you how to deploy an active-active Alfresco cluster with MySQL Galera Cluster (database), GlusterFS (filesystem) and HAproxy with Keepalived (load balancer) to achieve redundancy of all the required system components.

Please note that clustering of Alfresco instances is only available in the Alfresco Enterprise. Hazelcast is used …

I’ve been blogging a lot about some of the new things you can expect with Percona XtraDB Cluster 5.6 and Galera 3.x – and GA is coming …

January 6, 2014 By Severalnines

MySQL Cluster is a popular backend for FreeRADIUS, as it provides a scalable backend to store user and accounting data. However, there are situations when the backend database becomes a centralized datastore for additional applications and services, and needs to take a more general-purpose role. NDB usually works very well for FreeRADIUS data, but for wider use cases and reporting type applications, InnoDB can be a better storage engine. For users who need to keep their data in InnoDB and still benefit from a highly available clustered datastore, Galera Cluster can be an appropriate alternative.

In this post, we will show you how to deploy FreeRadius both with MySQL Cluster and Galera Cluster to store user and accounting data. All servers are running CentOS 6.4 64bit.

FreeRadius Deployment with Galera

We will deploy a two-node FreeRadius cluster …

This is a HOWTO about installing MariaDB Galera Cluster on Debian/Ubuntu.
It is because a lot of people had problems installing MariaDB Galera Cluster.
In the end elenst from #maria on freenode forced me to write a Howto :)
You will find out, installing MariaDB Galera Cluster is in fact quite easy and some kind of boring in the end.
This Howto is written (tested) on Debian 7.1 (Wheezy) and Ubuntu 12.04 (Precise).

What we need

In our setup we assume 3 nodes (node01, node02, node03) with one interface.
We assume following IP addresses: 172.16.8.5, 172.16.8.6 and 172.16.8.4. We need three packages installed on all nodes:

• rsync
• galera
• mariadb-galera-server

As Galera does not ship with the distribution repositories, go for the …

In many parts of the MySQL world, whether you have users, developers or administrators of MySQL, the season holidays are for family, relax, prayers, travel, or they are simply a moment where you can enjoy what you like or care most about.

For me, this time is dedicated to my family, but also to deeper thoughts around the strategies to adopt in short and long term. My work nowadays, as the work of many others, is ruled by quick decisions, by the "time to market” - whatever “market" means in a specific context. Decisions must be made in meetings that are time-boxed in one hour or even less. In the end, you accumulate so much work and high priority tasks that you do not have enough time to prepare the topics adequately.

I thought I could summarise my thoughts for the past year and for the near future, from a technical and from a business perspective.

A transient 2013To me, 2013 was a transient …

December 23, 2013 By Severalnines

This post is a continuation of our previous post on Online Schema Upgrade in Galera using TOI method. We will now show you how to perform a schema upgrade using the Rolling Schema Upgrade (RSU) method. This requires that the new schema is backward compatible with the old schema, so it requires a bit more planning than the TOI method. In some cases, you might need to turn off any connections to the target node. 

If you are using non-uniform hardware across your Galera cluster, RSU might be preferable as the more predictable process. RSU does not slow down your cluster.

As described in details in the previous …

December 19, 2013 By Severalnines

Database clusters are pretty sophisticated distributed systems with complex dependencies between nodes. The failure of a node will generally impact the overall cluster, as the remaining nodes need to reconfigure themselves to continue to operate without the failed node. Since re-introducing a node will also affect the existing cluster, the timing could therefore be dependent on the state of the other nodes in the cluster. Repair and restarts often needs to be performed in a particular order in compliance with the redundancy model of the cluster so as not to jeopardize the normal functioning of existing nodes.

Webinar: Repair and Recovery for your MySQL, MariaDB and MongoDB/TokuMX clusters

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December 10, 2013 By Severalnines

As a follow-up to the Webinar on Zero Downtime Schema Changes in Galera Cluster, we’ll now walk you through the detailed steps on how to update your schema. The two methods (TOI and RSU) have both their pros and cons, and given parameters like table size, indexes, key_buffer_size, disk speed, etc., it is possible to estimate the time taken for the schema to be upgraded. Also, please note that a schema change is non-transactional so it would not be possible to rollback the DDL if it fails midway. Therefore, it is always recommended to test the schema changes and ensure you have recoverable backups before performing this on your production clusters. 

This post examines the way DDL changes are propagated in Galera, and outlines the steps to upgrade the …