Implementing High Availability and Scalability with MariaDB Galera Cluster and MaxScale

Setting up MariaDB Galera Cluster with MaxScale for high availability and scalability involves several steps, from installing and configuring the Galera nodes to setting up MaxScale as a load balancer. Here's a step-by-step guide:

Step 1: Install MariaDB on All Nodes

1. Install MariaDB: Install MariaDB on each server that will be part of the Galera Cluster. Ensure that the version of MariaDB supports Galera.
   Shell

   sudo apt-get install mariadb-server

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   sudo apt-get install mariadb-server

Step 2: Configure Galera Cluster

1. Configure my.cnf: On each node, edit the MariaDB configuration file (/etc/my.cnf or /etc/mysql/mariadb.conf.d/50-server.cnf) to configure the Galera Cluster settings.
   Shell

   [mysqld] # Galera Provider Configuration wsrep_on=ON wsrep_provider=/usr/lib/galera/libgalera_smm.so # Cluster Connection Configuration wsrep_cluster_address="gcomm://node1,node2,node3" wsrep_cluster_name='galera_cluster' # Cluster Node Configuration wsrep_node_address="this_node_ip" wsrep_node_name='node_name' # InnoDB Configuration default_storage_engine=InnoDB innodb_autoinc_lock_mode=2 innodb_doublewrite=1 # SST Configuration wsrep_sst_method=rsync

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   [mysqld] # Galera Provider Configuration wsrep_on=ON wsrep_provider=/usr/lib/galera/libgalera_smm.so   # Cluster Connection Configuration wsrep_cluster_address="gcomm://node1,node2,node3" wsrep_cluster_name='galera_cluster'   # Cluster Node Configuration wsrep_node_address="this_node_ip" wsrep_node_name='node_name'   # InnoDB Configuration default_storage_engine=InnoDB innodb_autoinc_lock_mode=2 innodb_doublewrite=1   # SST Configuration wsrep_sst_method=rsync

2. Initialize the First Node: Start the first node with the -wsrep-new-cluster option:
   Shell

   sudo galera_new_cluster

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   sudo galera_new_cluster

3. Start Other Nodes: Start MariaDB normally on the other nodes. They should automatically join the cluster.
   Shell

   sudo systemctl start mariadb

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   sudo systemctl start mariadb

Step 3: Verify Cluster Status

• On each node, check the status of the Galera Cluster:
  Shell

  mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_%';"

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  mysql -u root -p -e "SHOW STATUS LIKE 'wsrep_%';"

• Ensure that all nodes are connected and synced.

Step 4: Install and Configure MaxScale

1. Install MaxScale: Install MaxScale on a separate server that will act as the load balancer and proxy.
   Shell

   sudo apt-get install maxscale

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   sudo apt-get install maxscale

2. Configure MaxScale: Edit the MaxScale configuration file (/etc/maxscale.cnf) to set up load balancing and connection routing.
   Shell

   [Galera Service] type=service router=readwritesplit servers=node1,node2,node3 user=maxscale_user passwd=maxscale_password max_slave_connections=100% [Galera Listener] type=listener service=Galera Service protocol=MySQLClient port=3306

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   [Galera Service] type=service router=readwritesplit servers=node1,node2,node3 user=maxscale_user passwd=maxscale_password max_slave_connections=100%   [Galera Listener] type=listener service=Galera Service protocol=MySQLClient port=3306

3. Create MaxScale User: On each Galera node, create a user for MaxScale with necessary permissions.
   Shell

   CREATE USER 'maxscale_user'@'maxscale_host' IDENTIFIED BY 'maxscale_password'; GRANT SELECT ON mysql.user TO 'maxscale_user'@'maxscale_host'; GRANT SELECT ON mysql.db TO 'maxscale_user'@'maxscale_host'; GRANT SELECT ON mysql.tables_priv TO 'maxscale_user'@'maxscale_host'; FLUSH PRIVILEGES;

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   CREATE USER 'maxscale_user'@'maxscale_host' IDENTIFIED BY 'maxscale_password'; GRANT SELECT ON mysql.user TO 'maxscale_user'@'maxscale_host'; GRANT SELECT ON mysql.db TO 'maxscale_user'@'maxscale_host'; GRANT SELECT ON mysql.tables_priv TO 'maxscale_user'@'maxscale_host'; FLUSH PRIVILEGES;

Step 5: Start and Verify MaxScale

• Start the MaxScale service and verify that it is routing connections correctly to the Galera nodes.

Step 6: Client Configuration

• Configure your database clients to connect to the MaxScale server instead of directly connecting to the Galera nodes.

Step 7: Test Failover and Redundancy

• Test the failover and redundancy of the setup by simulating node failures and ensuring that MaxScale redirects traffic to the remaining nodes without interruption.

Conclusion

Setting up MariaDB Galera Cluster with MaxScale involves installing and configuring the Galera nodes, setting up MaxScale as a load balancer, and ensuring proper client configuration. This setup ensures high availability and scalability by distributing the load across multiple nodes and providing automatic failover capabilities. Regular testing and monitoring of both the Galera Cluster and MaxScale are crucial to maintain the health and performance of the system.