Monitoring flow control in a Galera cluster is very important. If you do not, you will not understand why writes may sometimes be stalled. Percona XtraDB Cluster 5.6 provides 2 status variables for such monitoring: wsrep_flow_control_paused and wsrep_flow_control_paused_ns. Which one should you use?

What is flow control?

Flow control does not exist with regular MySQL replication, but only with Galera replication. It is simply the mechanism nodes are using when they are not able to keep up with the write load: to keep replication synchronous, the node that is starting to lag instructs the other nodes that writes should be paused for some time so it does not get too far behind.

If you are not familiar with this notion, you should read this …

Percona is glad to announce the new release of Percona XtraDB Cluster 5.6 on July 21st 2014. Binaries are available from downloads area or from our software repositories. We’re also happy to announce that Ubuntu 14.04 LTS users can now download, install, and upgrade Percona XtraDB Cluster 5.6 from Percona’s software repositories.

Based on Percona Server …

I recently worked on a case where one node of a Galera cluster had its schema desynchronized with the other nodes. And that was although Total Order Isolation method was in effect to perform the schema changes. Let’s see what happened.

Background

For those of you who are not familiar with how Galera can perform schema changes, here is a short recap:

• Two methods are available depending on the value of the wsrep_OSU_method setting. Both have benefits and drawbacks, it is not the main topic of this post.
• With TOI (Total Order Isolation), a DDL statement is performed at the same point in the replication flow on all nodes, giving strong guarantees that the schema is always identical on all nodes.
• With RSU (Rolling Schema Upgrade), a DDL statement is not replicated to the other nodes. Until the DDL statement has been executed on all nodes, the schema is not consistent everywhere (so …

This is the second part of my series on High Availability with mysqlnd_ms. In my first post, “Simple MySQL Master HA with mysqlnd_ms,” I showed a simple HA solution using asynchronous MySQL replication. This time we will see how to leverage an all-primary cluster where you can write to all nodes. In this post I used Percona XtraDB Cluster, but you should also be able to do the same with MySQL NDB Cluster or Tungsten Replicator.

To start with, here is the mysqlnd_ms configuration I used:

mysqlnd_ms_mm.ini

.  All of these files are available from my Github repository. Below, I have three Percona XtraDB Cluster nodes, …

In my previous post I showed you how to setup Percona XtraDB Cluster 5.6 on Docker. This time I will show you how to setup Percona ClusterControl and add the existing Percona XtraDB Cluster 5.6 that we’ve managed to setup from the previous post.

Let us note the following details about our existing containers:

• 172.17.0.2 dockerpxc1
• 172.17.0.3 dockerpxc2
• 172.17.0.4 dockerpxc3
• 172.17.0.5 dockerccui-test

A quick tip for everyone who has followed my previous blog on setting up Percona XtraDB Cluster 5.6 on Docker: I did not …

The Percona Backup Service managed service launched today. It ensures properly configured backups run successfully as scheduled on customer provided backup storage – whether on premise, in the cloud, or a hybrid. Backup issues or production data recovery are efficiently handled by Percona Managed Services technicians with deep knowledge of MySQL.

As we state in our white papers, “MySQL backup and recovery are a foundational piece of any infrastructure. A well-tested backup and recovery system can be the difference between a minor outage and the end of a business.” While MySQL backups are “foundational,” they …

So of course Percona has documentation that explain the process. The goal of this blog is to go into a little more detail in hopes that can help someone.

Hyperlinks for review:

• CentOS - http://www.percona.com/doc/percona-xtradb-cluster/5.5/howtos/cenots_howto.html
• Ubuntu - http://www.percona.com/doc/percona-xtradb-cluster/5.5/howtos/ubuntu_howto.html
• Installing Percona XtraDB Cluster from Binaries -   
  • http://www.percona.com/doc/percona-xtradb-cluster/5.5/installation.html
…

We recently open-sourced our percona-agent and if you check out the source code, you’ll find that it is written in the Go programming language (aka Golang). For those not up to speed, the percona-agent is a real-time client-side agent for Percona Cloud Tools.

Our requirements are quite demanding for our agents. This one is software that works on a real production server, so it must be fast, reliable, lightweight and easy to distribute. Surprisingly enough, binaries compiled by Go fit these characteristics.

There are of course alternatives that we considered. On the scripting side: Perl, Python, PHP, Ruby et al. These are not necessarily fast, and the distribution is also interesting. We have enough experience with …

I was interested to hear about semi-sync replication improvements in MySQL’s 5.7.4 DMR release and decided to check it out.  I previously blogged about poor semi-sync performance and was pretty disappointed from semi-sync’s performance across WAN distances back then, particularly with many client threads.

The Test

The basic environment of these tests was:

• AWS EC2 m3.medium instances
• Master in us-east-1, slave in us-west-1 (~78ms ping RTT)
• CentOS 6.5
• innodb_flush_log_at_trx_commit=1
• sync_binlog=1
• Semi-sync replication plugin installed and enabled.
• GTID’s enabled (except on 5.5)
• sysbench 0.5 update_index.lua test, 60 seconds, 250k table size.
• MySQL 5.7 was …

In my previous post, I blogged about using Percona Server with Docker and have shown you how fast and easy it was to create a virtual environment with just a few commands.

This time I will be showing you how to setup a three-node Percona XtraDB Cluster (PXC) 5.6 on the Docker open-source engine. Just to review Docker… “is an open-source engine that automates the deployment of any application as a lightweight, portable, self-sufficient container that will run virtually anywhere.”

In this case we will make use of a Dockerfile, think of this more like the Vagrantfile, it is a build script with a set of commands automating the creation of a new docker container.

For this case, we will use the …