How to Setup MariaDB Galera Cluster on Ubuntu 20.04

Load balancing and clustering are very important in a production environment to achieve high availability for your database system. MariaDB Galera Cluster provides a multi-master clustering solution and supports XtraDB/InnoDB storage engines. A multi-master cluster allows read and writes to any cluster node. If you modify data on any node, they are replicated to all other nodes. Galera cluster also supports cloud and WAN environments to build a distributed cluster across countries and continents.

In this post, we will show how to set up a three-node MariaDB Galera cluster on Ubuntu 20.04 server.

Prerequisites

  • Three servers running Ubuntu 20.04.
  • A root password is configured on the server.

Getting Started

Before starting, you will need to update your system packages to the latest version. You can update them using the following command:

apt-get update -y

Once your server is updated, you can proceed to the next step.

Install MariaDB Server

First, you will need to install the MariaDB server on all nodes. You can install it by running the following command:

apt-get install mariadb-server -y

Once the installation has been finished, start the MariaDB service and enable them to start at system reboot:

systemctl start mariadb
systemctl status mariadb

Next, you will need to secure the MariaDB installation and set a MariaDB root password on each node. You can do it with the following command:

mysql_secure_installation

You will be asked to set a MariaDB root password as shown below:

Enter current password for root (enter for none): 
Switch to unix_socket authentication [Y/n] n
Change the root password? [Y/n] Y
New password:
Re-enter new password:
Remove anonymous users? [Y/n] Y
Disallow root login remotely? [Y/n] Y
Remove test database and access to it? [Y/n] Y
Reload privilege tables now? [Y/n] Y

Once your MariaDB server is secured, you can proceed to the next step.

Configure Galera Cluster

Next, you will need to create a Galera configuration file on each node so that each node can communicate with each other.

On the first node, create a galera.cnf file using the following command:

nano /etc/mysql/conf.d/galera.cnf

Add the following lines:

[mysqld]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0

# Galera Provider Configuration
wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

# Galera Cluster Configuration
wsrep_cluster_name="galera_cluster"
wsrep_cluster_address="gcomm://node1-ip-address,node2-ip-address,node3-ip-address"

# Galera Synchronization Configuration
wsrep_sst_method=rsync

# Galera Node Configuration
wsrep_node_address="node1-ip-address"
wsrep_node_name="node1"

Save and close the file when you are finished.

On the second node, create a galera.cnf file using the following command:

nano /etc/mysql/conf.d/galera.cnf

Add the following lines:

[mysqld]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0

# Galera Provider Configuration
wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

# Galera Cluster Configuration
wsrep_cluster_name="galera_cluster"
wsrep_cluster_address="gcomm://node1-ip-address,node2-ip-address,node3-ip-address"

# Galera Synchronization Configuration
wsrep_sst_method=rsync

# Galera Node Configuration
wsrep_node_address="node2-ip-address"
wsrep_node_name="node2"

Save and close the file when you are finished.

On the third node, create a galera.cnf file using the following command:

nano /etc/mysql/conf.d/galera.cnf

Add the following lines:

[mysqld]
binlog_format=ROW
default-storage-engine=innodb
innodb_autoinc_lock_mode=2
bind-address=0.0.0.0

# Galera Provider Configuration
wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

# Galera Cluster Configuration
wsrep_cluster_name="galera_cluster"
wsrep_cluster_address="gcomm://node1-ip-address,node2-ip-address,node3-ip-address"

# Galera Synchronization Configuration
wsrep_sst_method=rsync

# Galera Node Configuration
wsrep_node_address="node3-ip-address"
wsrep_node_name="node3"

Save and close the file when you are finished.

Initialize the Galera Cluster

At this point, all nodes are configured to communicate with each other.

Next, you will need to stop the MariaDB service on all nodes. You can run the following command to stop the MariaDB service:

systemctl stop mariadb

On the first node, initialize the MariaDB Galera cluster with the following command:

galera_new_cluster

Now, check the status of the cluster with the following command:

mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_cluster_size'"

You should see the following output:

+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 1     |
+--------------------+-------+

On the second node, start the MariaDB service with the following command:

systemctl start mariadb

Next, check the status of the MariaDB Galera cluster with the following command:

mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_cluster_size'"

You should see the following output:

+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 2     |
+--------------------+-------+

On the third node, start the MariaDB service with the following command:

systemctl start mariadb

Next, check the status of the MariaDB Galera cluster with the following command:

mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_cluster_size'"

You should see the following output:

+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| wsrep_cluster_size | 3     |
+--------------------+-------+

At this point, the MariaDB Galera cluster is initialized. You can now proceed to the next step.

Verify Cluster Replication

Next, you will need to verify whether the replication is working or not.

On the First node, connect to the MariaDB with the following command:

mysql -u root -p

Once your are connected, create some database with the following command:

MariaDB [(none)]> create database db1;
MariaDB [(none)]> create database db2;

Next, exit from the MariaDB with the following command:

MariaDB [(none)]> exit;

Next, go to the second node and log in to the MariaDB with the following command:

mysql -u root -p

Next, run the following command to show all databases:

MariaDB [(none)]> show databases;

You should see that both databases that we have created on the first node are replicated on the second node:

+--------------------+
| Database           |
+--------------------+
| db1                |
| db2                |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
5 rows in set (0.001 sec)

Next, go to the third node and log in to the MariaDB with the following command:

mysql -u root -p

Next, run the following command to show all databases:

MariaDB [(none)]> show databases;

You should see that both databases that we have created on the first node are replicated on the third node:

+--------------------+
| Database           |
+--------------------+
| db1                |
| db2                |
| information_schema |
| mysql              |
| performance_schema |
+--------------------+
5 rows in set (0.001 sec)

Conclusion

In the above guide, we learned how to set up a three-node MariaDB Galera cluster on Ubuntu 20.04 server. You can now add more nodes to the MariaDB Galera cluster easily. Feel free to ask me if you have any questions.

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