How to install and configure Galera MySQL cluster on CentOS 7

To install and configure Galera MySQL Cluster on CentOS 7

MariaDB Galera Cluster is a synchronous multi-master cluster for MariaDB. It is available on Linux only, and only supports the XtraDB/InnoDB storage engines. In this tutorial am going install and configure Mariadb cluster 10.0 with 3 nodes on centos 7.

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 replication, on row level
• Direct client connections, native MariaDB look & feel

Before you begin with the configuration, make sure do the following steps :-

1. Disable the Selinux service.

2. Disable the firewall service.

Cluster details

Node1 192.168.7.211

Node2 192.168.7.212

Node3 192.168.7.213

Configuring Galera

Remove defaults MariaDB library files for all the three nodes

[root@server1 ~]# yum remove mariadb-libs -y

Once it is removed, create the MariaDB repository file for all three nodes as follows.

[root@server1 ~]# vim /etc/yum.repos.d/cluster.repo

[mariadb]
name = MariaDB
baseurl = http://yum.mariadb.org/10.0/centos7-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1

Now, install socat dependency package in all the 3 nodes. Use the following command for the same purpose.

[root@server1 ~]# yum install socat

Now is the time to install MariaDB Galera cluster 10.0 and its dependencies packages for all the nodes.

[root@server1 ~]# yum install MariaDB-Galera-server MariaDB-client rsync galera

Once it is installed, start the MariaDB services

[root@server1 ~]# systemctl start msyql

Execute the following commad to set MariaDB root login credential.

[root@server1 ~]# mysql_secure_installation

Now you can stop MariaDB service by running the following command. Do the same for all the three nodes.

[root@server1 ~]# systemctl stop msyql

You can now go on with Galera cluster configuration by adding the cluster address, cluster name, node address, etc. Don' t forget to do the same for the other two nodes as well.

[root@server1 ~]#  vim /etc/my.cnf.d/server.cnf
[mariadb-10.0]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
innodb_locks_unsafe_for_binlog=1
query_cache_size=0
query_cache_type=0
bind-address=0.0.0.0
datadir=/var/lib/mysql
innodb_log_file_size=100M
innodb_file_per_table
innodb_flush_log_at_trx_commit=2
wsrep_provider=/usr/lib64/galera/libgalera_smm.so
wsrep_cluster_address=" gcomm://192.168.7.211,192.168.7.212,192.168.7.213" 
wsrep_cluster_name=' galera_cluster' 
wsrep_node_address=' 192.168.7.211' 
wsrep_node_name=' node1' 
wsrep_sst_method=rsync
wsrep_sst_auth=db_user:admin

For configuring this cluster configuration on node2 and node3 do not forget to adjust the wsrep_node_address and wsrep_node_name variables. Before doing this steps stop the mysql service on both nodes.

For node2:

wsrep_node_address=' 192.168.7.212' 
wsrep_node_name=' node2' 

For db3

wsrep_node_address=' 192.168.7.213' 
wsrep_node_name=' node3' 

Once all the nodes are configured, you can start first cluster node.

This command should be executed only on node1.

[root@server1 ~]# /etc/init.d/mysql start &ndash wsrep-new-cluster

After that, sart MySQL service on both node2 and node3 as well. Run the following command on both the remaining nodes.

[root@server1 ~]# systemctl start mysql

Now check the status of configured galera cluster at node1. Repeat this command on node2 and node3 to check

# mysql

MariaDB [(none)]>  show status like ' wsrep%'  

| wsrep_incoming_addresses      | 192.168.7.212:3306,192.168.7.211:3306,192.168.7.213:3306 
 
| wsrep_local_state_comment     | Synced        

| wsrep_cluster_size            | 3                                                        

| wsrep_ready                   | ON          

Now, you can check replication process by creating a database from node1.

> mysql
>  create database sample1_db 
> show schema 

+--------------------+
| Database           |
+--------------------+
| sample1_db         |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+

After that login mysql into node2 and check the replication process there too.

>  show schemas 

+--------------------+
| Database           |
+--------------------+
| sample1_db         |
|                    |
|information_schema  |
| mysql              |
| performance_schema |
+--------------------+

Login mysql into node3 and check the replication process in it as well.

>  schow schemas 

+----------------------------+
| Database                   |
+----------------------------+
| sample1_db                 |
|                            |
|information_schema          |
| mysql                      |
| performance_schema         |
+----------------------------+

If you want to test more repilcatiom proess create a table and insert the values into that DB.

Node1

MariaDB [sample1_db]>  create table os(categories(char(25))) 

MariaDB [sample1_db]>  insert into os values(' Linux' ) 

MariaDB [sample1_db]>  select * from os 
+----------------+
| categories     |
+---------------+
| Linux          |
+----------------+

Node2

MariaDB [sample1_db]>  insert into os values(" MAC" ) 
Query OK, 1 row affected (0.02 sec)

MariaDB [sample1_db]>  select * from os 
+--------------+
| categories   |
+--------------+
| Linux        |
| MAC          |
+--------------+

Node3

MariaDB [sample1_db]>  insert into os values(' Windows' ) 
Query OK, 1 row affected (0.00 sec)

MariaDB [sample1_db]>  select * from os 
+---------------+
| categories    |
+---------------+
| Linux         |
| MAC           |
| Windows       |
+---------------+