The Question

You already know about the Continuent Connector which is the “secret sauce” that routes your application database traffic to the appropriate MySQL data source of your cluster.

Have you ever wondered how the Connector keeps track of the cluster configuration? How it always knows which host is the master (or masters in a Composite Multimaster topology), and which are slaves?

The Short Version

This information is actually held and maintained by the Managers, which monitor and take care of their local MySQL node.

Each one of the Connectors maintains a single connection to one, and only one, manager per data service. In the case of a Composite Multimaster topology, that will be one Manager chosen per site.

The Nitty Gritty

Every 3 seconds, each …

In the context of providing managed WordPress hosting services, at Presslabs we operate with lots of small to medium-sized databases, in a DB-per-service model, as we call it. The workloads are mostly reads, so we need to efficiently scale that. The MySQL® asynchronous replication model fits the bill very well, allowing us to scale horizontally from one server—with the obvious availability pitfalls—to tens of nodes. The next release of the stack is going to be open-sourced.

As we were already using Kubernetes, we were looking for an operator that could automate our DB deployments and auto-scaling. Those available were doing synchronous replication using MySQL group replication or Galera-based replication. Therefore, we decided to write our own operator.

Solution architecture

The …

With its fully integrated solution, Continuent Clustering allows fine control of slave replicas:

• Want to keep a slave read-only? Have a node that will never be switched-to and become a master itself? Still want to allow client applications to read data from it? We call it “Archive Slave”. It is particularly suitable for hosts that have low computational power and wouldn’t hold the write workload. All you need is to type a single cctrl command:

[LOGICAL:EXPERT] /alpha > datasource host3 set archive

Managers will never turn an archive slave into a master, whereas connector will still route to it for read-only traffic.

• Prefer a slave as much up-to-date as possible? Protected from reads and that will preferably be selected in case of switch or failover? That’s the stand-by node. By preventing read traffic, you dedicate computing and networking power to replication, keeping latency as low …

It’s very easy to install Percona Monitoring and Management (PMM) on DigitalOcean. If you’ve never used DigitalOcean before, you will find that it is user-friendly and not very expensive. For $5/month you can easily host your PMM on it, letting you monitor your simple infrastructure or try out PMM before implementing it to monitor your production environments.

Let’s prepare the DigitalOcean instance

Log in to DigitalOcean (DO) control panel and click “Create Droplet.”

Thanks to DO you can skip the boring OS setup and save time by using the Docker “One click app” in DO and the Docker image from PMM.

Note: After clicking on “Docker…” choose an instance size that accommodates your budget – PMM can run on as little as the 1GB 1vCPU instance!

Note: Scroll again!

Next step – select a nearby region …

Join Percona’s Senior Operations Engineer, Daniel Kowalewski as he presents Deploying MySQL in Production on Thursday, June 22, 2017 at 11:00 am PDT / 2:00 pm EDT (UTC-7).

Register Now  MySQL is famous for being something you can install and get going in less than five minutes in terms of development. But normally you want to run MySQL in production, and at scale. This requires some planning and knowledge. So why not learn the best practices around installation, configuration, deployment and backup?

This webinar is a soup-to-nuts talk that will have you going from zero to hero in no time. It includes discussion …

January 5, 2015 By Severalnines

Cloud storage is hot. Dropbox, Apple iCloud, Google Drive, Microsoft SkyDrive and Amazon Cloud Drive all offer cloud sharing platforms where you can store documents in the cloud and access them from all your devices. For enterprises who require full control, ownCloud is an open source solution that allows files to be stored on-premises and/or a backend cloud. 

In this blog post, we’ll show you how to deploy a high availability setup using ownCloud Community Edition. We will need to set up redundancy in each of the following layers:

• file storage
• web server
• database server
• load balancer

We will use five servers. ownCloud will run on three separate servers with MySQL Galera Cluster 5.6 and GlusterFS running on RHEL 6.5 64bit. ownCloud supports GlusterFS as primary storage. ClusterControl will be co-located …

July 22, 2014 By Severalnines

We just wanted to make it official: Severalnines ClusterControl now supports MariaDB 10!

As most of you know will know by now, MariaDB 10 is the newest and most advanced version of the popular MariaDB relational database system. Whilst remaining application-compatible with the MySQL database, it adds many new capabilities to address the most challenging web and enterprise application use cases. Cluster deployments would be based on MariaDB Galera Cluster 10, which is a complete merge of MariaDB 10.0.12 and Galera Cluster. 

ClusterControl for MariaDB Clusters

ClusterControl gives you the power to deploy, manage, monitor and scale entire MariaDB Galera clusters efficiently and …

May 23, 2014 By Severalnines

If you need to deploy a database cluster behind your corporate firewall, on servers with no internet access, then this blog is for you. Most of the installation tutorials out there require servers to have an internet connection, and that would not work very well with companies under strict policies and compliance guidelines. 

Our online Galera Configurator supports deployment without Internet connection for Percona XtraDB Cluster. You would need to prepare a minimum of four hosts (three DB nodes and one management node), generate a Deployment Package from the Configurator and copy it to the ClusterControl host. In this post, we will show you how to deploy Percona XtraDB Cluster 5.5 in an environment without internet connection on CentOS 6.5 (installed with minimal installation). Our setup is …

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 4, 2013 By Severalnines

As OpenStack deployments mature from evaluation/development to production environments supporting apps and services, high-availability becomes a key requirement. In a previous post, we showed you how to cluster the database backend - which is central to the operation of OpenStack. In that setup, you would have two controllers, while placing a 3-node Galera cluster on separate hosts. Now, it can be quite a leap to go from one VM with all services running on it, to a fully distributed setup with 5 VMs. The good news is that you can have a highly available setup starting with just 3 VMs.

In this post, we are going to show you how to cluster OpenStack Havana in a minimal node setup with 2 controllers and one compute node. Our controllers will be running all OpenStack services, as well as clustered RabbitMQ …