You are here

replication

Replication channel fail-over with Galera Cluster for MySQL

Sometimes it could be desirable to replicate from a Galera Cluster to a single MySQL slave or to an other Galera Cluster. Reasons for this measure could be:

Galera Cluster for MySQL

Undefined

Features

Galera is a synchronous multi-master replication Cluster for MySQL/InnoDB databases, having features like:

  • Synchronous replication
  • Active-active multi-master topology
  • Read and write to any cluster node
  • Automatic membership control, failed nodes drop from the cluster
  • Automatic node joining
  • True parallel replication, on row level
  • Direct client connections, native MySQL look & feel

Benefits

The benefits of these features are:

Check and fix MySQL Replication inconsistencies

Undefined

There are many different possibilities how you can achieve inconsistencies between Master and Slave in a MySQL replication, intentional and non-intentional ones. How to achieve them is not the topic of this article.

What we want to know is how can we detect inconsistencies or differences between Master and Slave and how can we fix them.

MySQL PERFORMANCE_SCHEMA Hints

Undefined

Accounts not properly closing connections [ 1 ]

SELECT ess.user, ess.host
     , (a.total_connections - a.current_connections) - ess.count_star as not_closed
     , ((a.total_connections - a.current_connections) - ess.count_star) * 100 /
       (a.total_connections - a.current_connections) as pct_not_closed

Galera Cluster discussions at FrOSCon 2012

During and after Henriks great talk about Galera Cluster at the FrOSCon 2012 in St. Augustin we found 2 important things related to Galera Cluster for MySQL:

SchoonerSQL

Undefined

There is a product out in the wild which is called SchoonerSQL [ 1 ] from an American company called Schooner Information Technology [ 2 ].

DOAG SIG MySQL - Replication: September 4, 2012 in Hamburg

Taxonomy upgrade extras: 

On Tuesday, September 4, 2012 the next DOAG SIG MySQL meeting will take place in Hamburg (Germany) with the topic Replication.

Possible presentations are: MySQL Replication, Galera Cluster, Replication with Oracle GoldenGate, Replication with Zimory Scale and Tungsten Replicator.

The event will presumably be located at the Hotel Böttcherhof at Wöhlerstrasse 2.

Building Galera Replication from Scratch

Introduction

MySQL/Galera synchronous Multi-Master Replication consists of 2 parts:

Galera - Synchronous Multi-Master Replication Cluster for MySQL/InnoDB

Undefined

Galera features

Galera provides the following features:

  • Synchronous replication
  • Active/active multi-master topology
  • Read and write to any cluster node
  • Automatic membership control, failed nodes drop from the cluster
  • Automatic node joining
  • True parallel row level replication
  • Direct client connections
  • Drop-in replacement for native MySQL

Galera benefits

Benefits using Galera Replication:

Be cautious when using Virtualized System with your Database

A customer rose a support case with a problem on his Master-Master set-up. The 2nd Master claims to have a problem:

MySQL Cluster - Cluster Ring-Replikation mit 2 Replikations-Kanälen

Vor ein paar Tagen hatte ich wieder einmal mit einer MySQL Cluster Replikation zu tun. Ich habe das schon eine Weile nicht mehr angelangt und war somit vorbereitet, wieder einmal ein paar Überraschungen zu erleben.

Diejenige, für welche MySQL Cluster - Cluster Ring-Replikationen das tägliche Brot ist, können diesen Artikel getrost überspringen. Alle anderen können möglicherweise von unseren Erfahrungen profitieren.

Wir hatten das folgende MySQL Cluster Konstrukt im Einsatz:

MySQL Cluster - Cluster circular replication with 2 replication channels

A few days ago I had to deal with MySQL Cluster replication. I did not do this for a while so I was prepared to expect some interesting surprises once again.

For those who MySQL Cluster - Cluster circular replication is the daily business they may skip this article. For all the others they possibly can profit from our learnings.

I am talking about the following MySQL Cluster set-up:

MySQL Support

English

What you get

  • Support for MySQL, Galera Cluster for MySQL, Percona Server and MariaDB.
  • Support via remote login (ssh) or Teamviewer and contact over phone, email, Skype or other instant messaging solutions.
  • We offer several different Support Levels with fast initial response times.

Supported MySQL Versions

We support the following MySQL versions:

MySQL Multi-Master – Single-Slave – Replication (Episode 2)

Introduction

One of the features that make MySQL so great is its easy replication set-up. If you are experienced and know-how to do it, it takes you about 15 minutes to set-up a slave. What you have in the end is a replication from one master to one or several slaves. So you can build a top-down data stream pyramid and spread your data on many slaves.

MySQL Replication

Active/active fail over cluster with MySQL Replication

Electing a slave as new master and aligning the other slaves to the new master

In a simple MySQL Replication set-up you have high-availability (HA) on the read side (r). But for the master which covers all the writes (w) and the time critical read (rt) there is no HA implemented. For some situations this can be OK. For example if you have rarely writes or if you can wait until a new Master is set up.

But in other cases you need a fast fail-over to a new master.

My thoughts about MySQL (Cluster) replication

Taxonomy upgrade extras: 

According to Johans wishes I write down my concerns about MySQL (Cluster) replication. These items are things I run again and again into it with customers:

MySQL Multi-Master - Single-Slave - Replication

MySQL provides its replication for High Availability (HA) and for read Scale-out. Generally it is known that in a MySQL replication you can only replicate from one Master to many slaves. In this paper it is shown how a set-up can look like to replicate from two masters to one slave.

Caution: Handle this information with care!!!

Subscribe to RSS - replication