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341 blog posts in 13 categories

Avoiding Deadlocks in Galera - Set up HAProxy for single-node writes and multi-node reads

Galera cluster has known limitations, one of them is that it uses cluster-wide optimistic locking. This may cause some transactions to rollback. With an increasing number of writeable masters, the transaction rollback rate may increase, especially if there is write contention on the same dataset. It is of course possible to retry the transaction and perhaps it will COMMIT in the retries, but this will add to the transaction latency. However, some designs are deadlock prone, e.g sequence tables. In this blog we present how you can minimize the risk for deadlocks due to the design of Galera. 

From the Field - Live Migration from MMM to MariaDB Galera Cluster

This is a guest post from Igor Shevtsov, a MySQL DBA based in Twickenham, UK. Igor has had the opportunity to deploy and manage different types of high availability MySQL solutions, and we invited him to share his experience. Igor can be contacted by email or LinkedIn.

Clustering MySQL Backend in OpenStack

OpenStack uses a database to store data for all OpenStack services such as compute nodes available, running instances, state and so on. The DB takes part in every user request, from listing all instances to creating new VMs, so it is central to the operation of OpenStack. In a high availability environment, the database should be clustered so as to avoid a single point of failure (SPOF). 

Migrating MySQL Galera Cluster to a new Data Center without Downtime

Are you tired and frustrated with your hosting or cloud provider? Have you seen a constant degradation in service levels and responsiveness? Or was the public cloud a bit too expensive after all, and you’re ready to move everything to in-house servers? Welcome to the club. Data migrations are painful and scary. Running a migration with scheduled downtime is hard enough as it is, but for certain applications, a prolonged period of downtime is not acceptable. Without the right strategy, a migration might leave you with inconsistent or lost data, hours of downtime and a negative impact to your business. This is why it is so hard to switch hosting or cloud providers. Once your data is in somebody else’s infrastructure, they’ve got you by the balls.

How to Clone Your Database

If you are managing a production database, chances are high that you’ve had to clone your database to a different server than the production server. The basic method of creating a clone is to restore a database from a recent backup on to a different database server. Other methods include replicating from a source database while it is up, in which case it is important the original database be unaffected by any cloning procedure.

How to Scale Joomla on Multiple Servers

Joomla! is estimated to be the second most used CMS on the internet after WordPress, with users like eBay, IKEA, Sony, McDonald’s and Pizza Hut. In this post, we will describe how to scale Joomla on multiple servers. This architecture not only allows the CMS to handle more users, by load-balancing traffic across multiple servers. It also brings high availability by providing fail-over between servers.

How to Cluster Magento, nginx and MySQL on Multiple Servers for High Availability

Magento is an open-source e-commerce platform built on Zend PHP and MySQL. It is widely adopted by online retailers with some 150,000 sites known to use it. Single server setups are easy to set up, but if your store is a huge success, then you probably need to think about clustering your environment with multiple servers. Clustering is done at the web, database and file-system level, as all web nodes need access to catalog images. 

Scaling Wordpress and MySQL on Multiple Servers for Performance

Over the years, WordPress has evolved from a simple blogging platform to a CMS. Over seven million sites use it today, including the likes of CNN, Forbes, The New York Times and eBay. So, how do you scale Wordpress on multiple servers for high performance? 

Using HAProxy with Your Database Cluster

Severalnines s9s_haproxy script allows you to install HAProxy and loadbalance over the MySQL servers in your cluster. To learn more about HAProxy and SQL load balancing, see this HAProxy Tutorial.

Scaling Drupal on Multiple Servers with Galera Cluster for MySQL

This post shows you how to move from a single instance Drupal/MySQL to a multi-server environment. A well designed multi-server deployment not only allows Drupal to scale, but will also enhance redundancy by removing single points of failure. Components used are Apache, PHP, csync2, lsyncd, Keepalived, HAproxy,&MySQL Galera ClusterClusterControl.