Severalnines Blog
The automation and management blog for open source databases

Severalnines blog

Filter by:
Apply (1) filters
84 blog posts in 13 categories

How to Deploy Galera Cluster for MySQL using Docker Containers

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. 

How to Cluster Liferay with MySQL Galera and Ceph for High Availability and Performance

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. 

Active-active Alfresco cluster with MySQL Galera and GlusterFS

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.

Deploying an Active-Active FreeRadius Cluster with MySQL NDB or Galera

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.

Online Schema Upgrade in MySQL Galera Cluster using TOI Method

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.

Posted in:

Point-in-time Recovery in MySQL Galera Cluster

Data protection is vital for DB admins, especially when it involves data that is accessed and updated 24 hours a day. Clustering and replication are techniques that provide protection against failures, but what if a user or DBA issues a detrimental command against one of the databases? A user might erroneously delete or update the contents of one or more tables, drop database objects that are still needed during an update to an application, or run a large batch update that fails midway. How do we recover lost data?

Understanding gcache in Galera

Galera uses a preallocated file with a specific size called gcache, used to store the writesets in circular buffer style. By default, its size is 128MB. In this post, we are going to explore how to leverage gcache to improve the operation of a Galera cluster.

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.

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.