September 17, 2013 By Severalnines

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. 

Test Case

Here is a simple test case. We have a table that contains a column and a row that hold a number and is regularly updated to provide …

Two of the more popular solutions are  MySQL Master HA and Percona Replication Manager.

MySQL Master HA

MHA is based on a set of Perl scripts that monitors for replication and server health. When a failover scenario will happen, it can do automatic failover to a slave OR from a selection of slaves you have configured to make as the new master. The good thing about this is, after the initial failover, there will be no succeeding attempts to fail back, this is to protect your data and consistency of the cluster. You can also configure to only have manual failover for scheduled maintenance and the like. Between PRM and MHA, MHA is really easier to manage.

http://code.google.com/p/mysql-master-ha/

Percona Replication Manager

PRM is based on …

Good afternoon Oscon attendees - in particular attendees of my High Availability in MySQL tutorial!

Attached you can find a spreadsheet (both LibreOffice, Excel) that we will use at the end of the tutorial. You can also download the slides, in case you wish to browse them at your own pace.

July 2, 2013 By Severalnines

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.

This post is similar to our previous posts on web application scalability and high availability:

• Drupal - Apache, MySQL Galera Cluster, csync2 with lsyncd
• Wordpress - Apache, Percona XtraDB Cluster, …

June 28, 2013 By Severalnines

This article describes how to setup replication between a regular MySQL server and a Galera Cluster. The regular MySQL Server is the MASTER , and one of the Galera nodes will be the SLAVE:

In this example we have the following hosts:

• REGULAR MASTER: 10.0.1.10
• GALERA NODE #1 (SLAVE): 10.0.1.11

read more

June 17, 2013 By Severalnines

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. 

This post is similar to our previous posts on scaling Drupal and WordPress performance, and focuses on how to scale Magento on multiple servers. The software used is Magento version 1.7.0.2 , nginx, HAProxy, MySQL Galera …

The aim of this post is to enumerate real-world usage of Percona XtraDB Cluster (PXC), and also to solicit use cases from the readers. One of the prominent usages in the production environment that we have come across (and our Percona consultants have assisted) is that of HP Cloud. There is a post about it here by Patrick Galbraith of HP. The post focuses on their deployment of PXC for HP Cloud DNS. The post focuses on the key aspects of synchronous replication setup with high-availability guarantees like split-brain immunity.

Nobody likes to debug async replication while its broken or …

June 11, 2013 By Severalnines

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? 

This post is similar to our previous post on Drupal, Scaling Drupal on Multiple Servers with Galera Cluster for MySQL but we will focus on Wordpress, Percona XtraDB Cluster and GlusterFS using Debian Squeeze 64bit.

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Teradata Q1 disappoints. Actian acquires ParAccel. And more.

For 451 Research clients: Acquisitive Actian adds ParAccel to its growing database portfolio bit.ly/YgeY7k

— Matt Aslett (@maslett) April 29, 2013

For 451 Research clients: Tokutek releases TokuDB database storage engine as open source bit.ly/102xsSW

— Matt Aslett (@maslett) May 1, 2013

For 451 Research clients: Codership replicates partnership success with Galera Cluster for MySQL bit.ly/15dI8Hh

— Matt Aslett (@maslett) May …

Galera/Percona XtraDB Cluster (PXC) for MySQL is a hot thing right now and some users jump right in without enough testing. Consequently, they’re more likely to either suffer failure or issues that prevent them from moving forward. If you are thinking of migrating your workload to Percona XtraDB Cluster, make sure to go through these basics.

log_slave_updates is REQUIRED

You need to have log_slave_updates enabled on the cluster node acting as async slave for replicated events from the async master to be applied to the other nodes, that is if you have more than one PXC node. This is because before Galera can create writesets for the replicated events, binlog events must be generated for the transactions first. Under …