February 27, 2014 By Severalnines

Stockholm MongoDB User Group Meetup: “MongoDB and Hadoop” Monday, March 3, 2014 starting @ 5:00 PM

Join us next Monday as we host the Stockholm MongoDB User Group Meetup in Kista, or the Wireless Valley as it is also referred to. 

Our very own Vinay Joosery will be speaking about how to best automate the management & deployment of database clusters, specifically MongoDB clusters though the same principles apply for MySQL, MariaDB and Percona XtraDB based clusters. Henrik Ingo of MongoDB will be talking about Analytics with MongoDB & Hadoop. And Jim Dowling, a Senior Researcher at the Swedish Institute of Computer Science, will talk about a Hadoop PaaS platform. 

So whether you’re from the MySQL or NoSQL world, there’ll be plenty of good content here to walk away with in addition to …

February 18, 2014 By Severalnines

Virtual Machines are great, and very useful when trying out new software. However, they might be an unnecessarily heavyweight solution when testing clusters, especially if these consist of multiple nodes running exactly the same software. Each VM runs a full-blown OS image. On the other hand, Linux Containers (LXC) are an efficient alternative to OS-level virtualization and can run multiple isolated systems on a single host. Docker is a wrapper around LXC, it automates the deployment of applications inside containers. 

A notable advantage if you run with Docker + LXC is you can run many containers on a single host. They all share the same OS as the host, and when possible, the same binaries. Deployment can be extremely fast. Using Docker could be a good method if you want to spin multiple Galera nodes within a single host. 

In this post, we will create MySQL Galera Cluster …

February 13, 2014 By Severalnines

Galera is slowly but surely establishing itself as a credible replacement for traditional MySQL master-slave architectures. 

The benefits are clear - a true multi-master InnoDB setup with built-in fail-over, potentially across data centers. 

But how do you migrate? Does the schema or application change? What are the limitations? Can migration be done online, without service interruption? What are the potential risks, and how to address those?

Webinar: Migrating to MySQL, MariaDB Galera and/or Percona XtraDB Cluster

Tuesday, March 11th 2014

Register now - Europe/MEA/APAC

Register now - North …

February 3, 2014 By Severalnines

Liferay is an open-source content management system written in Java. It is used by a number of high traffic sites, as this survey suggests. 

Clustering Liferay and other components such as the database and the file system is a good way to handle the performance requirements of a high traffic site. The latest Liferay version has introduced features that simplify clustering, such as built-in support for Ehcache clustering, Lucene replication, read/write splitting capabilities for database (in case if you run on master-slave architecture) and support for various file systems for the portal repository. 

In this post, we are going to show you how to cluster Liferay in a multi-node load-balanced setup. The database backend will be based on Galera Cluster for MySQL, and the file …

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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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 …

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 …

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 …