MariaDB Galera Cluster on Ubuntu 24.04

MariaDB Galera Cluster provides synchronous multi-master replication for MariaDB. In this guide, we will set up a 3-node Galera cluster on Ubuntu 24.04 servers.

Cluster Architecture

We will create a 3-node MariaDB Galera cluster:

                MariaDB Galera Cluster
                ======================

          ┌──────────────────────────┐
          │        Node 1             │
          │  192.168.1.101            │
          │  mariadb-node1            │
          └────────────┬─────────────┘
                       │
             ┌─────────┴─────────┐
             │                   │
             ▼                   ▼
    ┌────────────────┐   ┌────────────────┐
    │    Node 2      │   │    Node 3      │
    │ 192.168.1.102  │   │ 192.168.1.103  │
    │ mariadb-node2  │   │ mariadb-node3  │
    └────────────────┘   └────────────────┘

Galera provides synchronous replication between the nodes.

Server Information

Node	Hostname	IP Address
Node 1	mariadb-node1	192.168.1.101
Node 2	mariadb-node2	192.168.1.102
Node 3	mariadb-node3	192.168.1.103

Run the following installation steps on all three servers unless specifically mentioned otherwise.

---

1. Update Ubuntu

On Node 1, Node 2, and Node 3:

sudo apt update
sudo apt upgrade -y

Check Ubuntu version:

lsb_release -a

You should see Ubuntu 24.04.

---

2. Set Hostnames

Node 1 - On 192.168.1.101:

sudo hostnamectl set-hostname mariadb-node1

Node 2 - On 192.168.1.102:

sudo hostnamectl set-hostname mariadb-node2

Node 3 - On 192.168.1.103:

sudo hostnamectl set-hostname mariadb-node3

Verify on each node:

hostname

---

3. Configure /etc/hosts

This is important so that every node can resolve the other nodes.

Run this on all three servers:

sudo nano /etc/hosts

Add:

192.168.1.101 mariadb-node1
192.168.1.102 mariadb-node2
192.168.1.103 mariadb-node3

Test connectivity:

ping -c 3 mariadb-node1
ping -c 3 mariadb-node2
ping -c 3 mariadb-node3

All nodes should be reachable.

---

4. Install MariaDB

Run on all three nodes:

sudo apt install mariadb-server mariadb-client galera-4 -y

Check MariaDB:

mariadb --version

Check Galera:

dpkg -l | grep galera

---

5. Enable MariaDB

On all nodes:

sudo systemctl enable mariadb

Do not worry if we stop MariaDB later during the cluster configuration.

---

6. Configure Firewall

If UFW is enabled, Galera needs communication between the nodes.

On all three nodes, allow:

sudo ufw allow from 192.168.1.0/24 to any port 3306 proto tcp
sudo ufw allow from 192.168.1.0/24 to any port 4567 proto tcp
sudo ufw allow from 192.168.1.0/24 to any port 4567 proto udp
sudo ufw allow from 192.168.1.0/24 to any port 4568 proto tcp
sudo ufw allow from 192.168.1.0/24 to any port 4444 proto tcp

Check:

sudo ufw status

Galera Ports

Port	Purpose
3306	MariaDB client connections
4567	Galera replication
4568	Galera IST (Incremental State Transfer)
4444	Galera SST (State Snapshot Transfer)

If your servers are on a different network, replace 192.168.1.0/24 with your actual private network.

---

7. Stop MariaDB

Do this on all three nodes:

sudo systemctl stop mariadb

Verify:

sudo systemctl status mariadb

It should show that MariaDB is stopped.

---

8. Configure Galera on Node 1

On Node 1 only:

sudo nano /etc/mysql/mariadb.conf.d/60-galera.cnf

Add:

[mysqld]

bind-address=0.0.0.0

binlog_format=ROW
default-storage-engine=InnoDB

innodb_autoinc_lock_mode=2
innodb_flush_log_at_trx_commit=2
innodb_file_per_table=1

wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

wsrep_cluster_name="mariadb_cluster"

wsrep_cluster_address="gcomm://192.168.1.101,192.168.1.102,192.168.1.103"

wsrep_node_name="mariadb-node1"
wsrep_node_address="192.168.1.101"

wsrep_sst_method=rsync

Save: Ctrl + O → Enter → Ctrl + X

---

9. Configure Galera on Node 2

On Node 2:

sudo nano /etc/mysql/mariadb.conf.d/60-galera.cnf

Add:

[mysqld]

bind-address=0.0.0.0

binlog_format=ROW
default-storage-engine=InnoDB

innodb_autoinc_lock_mode=2
innodb_flush_log_at_trx_commit=2
innodb_file_per_table=1

wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

wsrep_cluster_name="mariadb_cluster"

wsrep_cluster_address="gcomm://192.168.1.101,192.168.1.102,192.168.1.103"

wsrep_node_name="mariadb-node2"
wsrep_node_address="192.168.1.102"

wsrep_sst_method=rsync

---

10. Configure Galera on Node 3

On Node 3:

sudo nano /etc/mysql/mariadb.conf.d/60-galera.cnf

Add:

[mysqld]

bind-address=0.0.0.0

binlog_format=ROW
default-storage-engine=InnoDB

innodb_autoinc_lock_mode=2
innodb_flush_log_at_trx_commit=2
innodb_file_per_table=1

wsrep_on=ON
wsrep_provider=/usr/lib/galera/libgalera_smm.so

wsrep_cluster_name="mariadb_cluster"

wsrep_cluster_address="gcomm://192.168.1.101,192.168.1.102,192.168.1.103"

wsrep_node_name="mariadb-node3"
wsrep_node_address="192.168.1.103"

wsrep_sst_method=rsync

---

11. Verify Configuration

On each node, verify the MariaDB service configuration:

sudo systemctl status mariadb

---

12. Bootstrap the First Node

This is the most important step. We need to bootstrap Node 1 first.

On Node 1:

sudo galera_new_cluster

Check:

sudo systemctl status mariadb

It should be running.

---

13. Check Node 1 Cluster Status

Connect to MariaDB:

sudo mariadb

Run:

SHOW STATUS LIKE 'wsrep_cluster_size';

Initially, you should see:

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

Check cluster status:

SHOW STATUS LIKE 'wsrep_cluster_status';

Expected:

+---------------------+--------+
| Variable_name       | Value  |
+---------------------+--------+
| wsrep_cluster_status| Primary|
+---------------------+--------+

Check node state:

SHOW STATUS LIKE 'wsrep_local_state_comment';

Expected:

+---------------------------+--------+
| Variable_name             | Value  |
+---------------------------+--------+
| wsrep_local_state_comment | Synced |
+---------------------------+--------+

Exit:

EXIT;

---

14. Start Node 2

Go to Node 2:

sudo systemctl start mariadb

Check:

sudo systemctl status mariadb

Then:

sudo mariadb

Run:

SHOW STATUS LIKE 'wsrep_cluster_size';

You should now see:

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

Also check:

SHOW STATUS LIKE 'wsrep_local_state_comment';

Expected: Synced

Exit:

EXIT;

---

15. Start Node 3

Go to Node 3:

sudo systemctl start mariadb

Check:

sudo systemctl status mariadb

Then:

sudo mariadb

Run:

SHOW STATUS LIKE 'wsrep_cluster_size';

Expected:

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

Check:

SHOW STATUS LIKE 'wsrep_cluster_status';

Expected: Primary

And:

SHOW STATUS LIKE 'wsrep_local_state_comment';

Expected: Synced

---

16. Check the Complete Cluster

Run this on any node:

sudo mariadb

Then:

SHOW STATUS LIKE 'wsrep%';

Important values:

Variable	Expected Value
wsrep_cluster_size	3
wsrep_cluster_status	Primary
wsrep_local_state_comment	Synced
wsrep_ready	ON

The desired state:

+------------------------------+----------------+
| Variable_name                | Value          |
+------------------------------+----------------+
| wsrep_cluster_size           | 3              |
| wsrep_cluster_status         | Primary        |
| wsrep_local_state_comment    | Synced         |
| wsrep_ready                  | ON             |
+------------------------------+----------------+

---

17. Test Database Replication

Now we will test whether data created on Node 1 appears on Node 2 and Node 3.

On Node 1:

sudo mariadb

Create a database:

CREATE DATABASE cluster_test;
USE cluster_test;

Create a table:

CREATE TABLE users (
    id INT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(100)
);

Insert data:

INSERT INTO users (name) VALUES ('Alice');

Check:

SELECT * FROM users;

You should see:

+----+-------+
| id | name  |
+----+-------+
|  1 | Alice |
+----+-------+

Exit:

EXIT;

---

18. Check Node 2

Connect to Node 2:

sudo mariadb

Run:

USE cluster_test;
SELECT * FROM users;

You should see:

+----+-------+
| id | name  |
+----+-------+
|  1 | Alice |
+----+-------+

This means replication is working.

---

19. Check Node 3

On Node 3:

sudo mariadb

Run:

USE cluster_test;
SELECT * FROM users;

You should also see Alice.

---

20. Test Replication in the Other Direction

On Node 3:

USE cluster_test;
INSERT INTO users (name) VALUES ('Bob');
SELECT * FROM users;

Expected:

+----+-------+
| id | name  |
+----+-------+
|  1 | Alice |
|  2 | Bob   |
+----+-------+

Now go to Node 1:

sudo mariadb

Run:

USE cluster_test;
SELECT * FROM users;

You should see both Alice and Bob.

---

21. Test Node Failure

Now we can test what happens when one node goes down.

Stop Node 3:

sudo systemctl stop mariadb

On Node 1, check:

sudo mariadb

SHOW STATUS LIKE 'wsrep_cluster_size';

Expected:

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

The cluster should remain operational because 2 out of 3 nodes are still available.

---

22. Bring Node 3 Back

On Node 3:

sudo systemctl start mariadb

Wait a few seconds, then check:

sudo mariadb

SHOW STATUS LIKE 'wsrep_local_state_comment';

Expected: Synced

Then:

SHOW STATUS LIKE 'wsrep_cluster_size';

Expected: 3

---

23. Important Warning About Bootstrapping

Do not run this casually:

sudo galera_new_cluster

This command is used to bootstrap a new primary cluster. You normally use it when starting a completely new cluster or when the entire cluster has gone down and you need to recover it.

Do not run galera_new_cluster on Node 2 or Node 3 while Node 1’s cluster is already running.

---

24. Useful Troubleshooting Commands

Command	Purpose
sudo systemctl status mariadb	Check MariaDB status
sudo journalctl -u mariadb -n 100 --no-pager	Check recent MariaDB logs
sudo journalctl -u mariadb -f	Follow MariaDB logs
sudo mariadb -e "SHOW STATUS LIKE 'wsrep%';"	Check Galera status
sudo mariadb -e "SHOW STATUS LIKE 'wsrep_cluster_size';"	Check cluster size
sudo mariadb -e "SHOW STATUS LIKE 'wsrep_cluster_status';"	Check cluster state
sudo mariadb -e "SHOW STATUS LIKE 'wsrep_local_state_comment';"	Check local node state

---

25. Final Expected Result

After everything is configured, all three nodes should report:

Cluster Name:        mariadb_cluster

Node 1:              192.168.1.101
Node 2:              192.168.1.102
Node 3:              192.168.1.103

Cluster Size:        3
Cluster Status:      Primary
Node State:          Synced
Galera Ready:        ON

And if you create data on one node:

Node 1
  ↓
Galera
  ↓
Node 2 + Node 3

The data should be available on the other nodes.

---

Important Production Note

This is a learning/lab setup. Before using it in production, you should additionally configure:

• Secure SST authentication
• TLS/encryption
• Proper firewall restrictions
• Backups
• Monitoring
• Quorum/recovery procedures
• An appropriate MariaDB/Galera configuration for your workload

Also, don’t expose MariaDB port 3306 to the public internet. Keep cluster traffic on a trusted/private network whenever possible.

---

Conclusion

You have successfully set up a 3-node MariaDB Galera Cluster on Ubuntu 24.04. The cluster provides synchronous multi-master replication, meaning data written to any node is immediately available on all other nodes. This setup is ideal for high-availability database environments where you need fault tolerance and load balancing.