How to Setup MariaDB Galera Cluster on CentOS 7

MariaDB Galera Cluster 10.0.12 Stable has been released and available for production use. MariaDB is a relational database management system (RDBMS). Generally we use single node of database server for small application but think about application which have thousands of users keep online at a time, In that situation we need a structure which will capable to handle this load and provides high availability. So we need to add multiple database servers interconnected with each other and keep synchronized, so in case any server goes down other servers can take place of them and provide services to users.
This article will help you to set up MariaDB Galera Cluster  with 3 nodes running with CentOS 7. Cluster server details are as following.
    • Cluster DB1: 192.168.1.10 ( HostName: db1.sysadmin.com.vn )
    • Cluster DB2: 192.168.1.20 ( HostName: db2.sysadmin.com.vn )
    • Cluster DB3: 192.168.1.30 ( HostName: db3.sysadmin.com.vn )
Note: Step 1/2/3 has to be done on all cluster nodes and remaining steps are node specific.

Step 1: Add MariaDB Repositories

Create a mariadb repository /etc/yum.repos.d/mariadb.repo using following content in your system. Below repository will work on CentOS 6.x systems, For othe
r system use repository generation tool and add to your system.
For CentOS 6 – 64bit
[mariadb]name = MariaDB
baseurl = http://yum.mariadb.org/10.0/centos6-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1
For CentOS 6 – 32bit
[mariadb]name = MariaDB
baseurl = http://yum.mariadb.org/10.0/centos6-x86
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1

Step 2: Install MariaDB and Galera

Before installing MariaDB Galera cluster packages, remove any existing MySQL or MariaDB packages installed on system. After that use following command to install on all nodes.
# yum install MariaDB-Galera-server MariaDB-client galera

Step 3: Initial MariaDB Configuration

After successfully installing packages in above steps do the some initial MariaDB configurations. Use following command and follow the instructions on all nodes of cluster. If will prompt to set root account password also.
# service mysql start
# mysql_secure_installation
After that create a user in MariaDB on all nodes, which can access database from your network in cluster.
# mysql -u root -p

MariaDB [(none)]> GRANT ALL PRIVILEGES ON *.* TO 'cluster'@'%' IDENTIFIED BY 'password' WITH GRANT OPTION;
MariaDB [(none)]> FLUSH PRIVILEGES;
MariaDB [(none)]> exit
and stop MariaDB service before starting cluster configuration
# service mysql stop

Step 4: Setup MariaDB Galera Cluster on DB1

Lets start setup MariaDB Galera cluster from DB1 server. Edit MariaDB server configuration file and add following values under [mariadb] section.
[root@db1 ~]# vim /etc/my.cnf.d/server.cnf
query_cache_size=0
binlog_format=ROW
default_storage_engine=innodb
innodb_autoinc_lock_mode=2
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.1.10,192.168.1.20,192.168.1.30"
wsrep_cluster_name='cluster1'
wsrep_node_address='192.168.1.10'
wsrep_node_name='db1'
wsrep_sst_method=rsync
wsrep_sst_auth=cluster:password
Start cluster using following command.
[root@db1 ~]# /etc/init.d/mysql bootstrap
Bootstrapping the clusterStarting MySQL.... SUCCESS!
If you get any problem during startup check MariaDB error log file /var/lib/mysql/<hostname>.err

Step 5: Add DB2 in MariaDB Cluster

After successfully starting cluster on DB1. Start configuration on DB2. Edit MariaDB server configuration file and add following values under [mariadb] section. All the settings are similar to DB1 except wsrep_node_address, wsrep_cluster_address and wsrep_node_name.
[root@db2 ~]# vim /etc/my.cnf.d/server.cnf
query_cache_size=0
binlog_format=ROW
default_storage_engine=innodb
innodb_autoinc_lock_mode=2
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.1.10,192.168.1.20,192.168.1.30"
wsrep_cluster_name='cluster1'
wsrep_node_address='192.168.1.20'
wsrep_node_name='db2'
wsrep_sst_method=rsync
wsrep_sst_auth=cluster:password

Start cluster using following command.
[root@db2 ~]# /etc/init.d/mysql start
Starting MySQL..... SUCCESS!

Step 6: Add DB3 in MariaDB Cluster

This server is optional, If you want only two server in cluster, you can ignore this step, but you need to remove third server ip from DB1/DB2 configuration files. To add this server make changes same as DB2.
[root@db3 ~]# vim /etc/my.cnf.d/server.cnf
query_cache_size=0
binlog_format=ROW
default_storage_engine=innodb
innodb_autoinc_lock_mode=2
wsrep_provider=/usr/lib/galera/libgalera_smm.so
wsrep_cluster_address="gcomm://192.168.1.10,192.168.1.20,192.168.1.30"
wsrep_cluster_name='cluster1'
wsrep_node_address='192.168.1.30'
wsrep_node_name='db2'
wsrep_sst_method=rsync
wsrep_sst_auth=cluster:password
Start cluster using following command.
[root@db3 ~]# /etc/init.d/mysql start
Starting MySQL..... SUCCESS!

Step 7: Test MariaDB Galera Cluster Setup

At this stage your cluster setup has been completed and running properly. Now you can test the cluster setup by creating database and tables at any server in cluster, it will replicate immediately to all servers in cluster.