LinuxPizza

Galera is a part of MariaDB and enables active/active/active replikation of databases between servers. While it necessarily dont provide any performance gains, it instead enabled a HA for the databases.

This guide assumes that you run Debian 10, which comes with MariaDB 10.3

Install MariaDB 10.3

    apt-get update
    apt-get install mariadb-server galera

Configuration

It is always STRONGLY recommended to run an odd number of nodes, and atleast three nodes. This is to avoid split-brain and alot of headache and frustration in the future. Please, just set up three nodes and dont bother with a 2 node cluster.

Sure, more servers = the slower the writes will be. So it is recommended to go with atleast 3 nodes, and maximum

Galera configuration

In order to create our galera-cluster, we have to create the following file: /etc/mysql/conf.d/galera.cnf, add the following content. Just be sure that you edit it to fit your needs.

    [mysqld]
    binlog_format=ROW
    default-storage-engine=innodb
    innodb_autoinc_lock_mode=2
    innodb_doublewrite=1
    query_cache_size=0
    query_cache_type=0
    bind-address=0.0.0.0
    wsrep_on=ON
    wsrep_provider=/usr/lib/galera/libgalera_smm.so
    wsrep_cluster_name="galera1"
    wsrep_cluster_address=gcomm://192.168.2.11,192.168.2.12,192.168.2.13
    wsrep_sst_method=rsync
    wsrep_node_address=192.168.2.11

You might want to edit the “listen” address for the MariaDB installation, it is usually found in /etc/mysql/mariadb.cnf.

Configure the other servers accordingly, and execute systemctl restart mariadb-server on all nodes. You might want to execute galera_new_cluster on one of the nodes and restart all the nodes again.

Now, you can try to create a database on one node:

    create database testdb

And you should be able to see it from the other nodes:

    show databases;