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MariaDB is a relational database management system (RDBMS) and MariaDB Galera Cluster is a synchronous multi-master cluster for MariaDB. It is available on Linux only, and only supports theXtraDB/InnoDB storage engines. This article explains how to setup MariaDB Galera Cluster 10.0 with 3 nodes running on CentOS 6.5 x86_64 resulting in a HA (high-availability) database cluster. CLUSTER DETAILS We using 3 freshly deployed VMs running a minimal install of CentOS 6.5 x86_64. Cluster node 1 has hostname db1 and IP address 1.1.1.1 Cluster node 2 has hostname db2 and IP address 1.1.1.2 Cluster node 3 has hostname db3 and IP address 1.1.1.3Step 1: Add MariaDB Repositories Create a mariadb repository /etc/yum.repos.d/mariadb.repo using following content in 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=1For 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=1Step 2 – Set SELinux in permissive mode Before starting the setup put SELinux into permissive mode on all nodes: sudo setenforce0Step 3 – Install MariaDB Galera Cluster 10.0 software If you did a CentOS 6 minimal installation then make sure you install the socat package from the EPEL repository before proceeding with installing the MariaDB Galera Cluster 10.0 software. You can install socat package directly from EPEL with the following command (for x86_64): sudo yum install http://dl.fedoraproject.org/pub/epel/6/x86_64/socat-1.7.2.3-1.el6.x86_64.rpmOn CentOS 7 you can install socat package with following command. sudo yum install socatInstall the MariaDB Galera Cluster 10.0 software by executing the following command on all nodes: sudo yum install MariaDB-Galera-server MariaDB-client rsync galeraStep 4: Setup MariaDB security Start the MySQL ( init script in MariaDB 10.0 is still called mysql) sudo service mysql startRun the mysql_secure_installation script so we can improve the security. Run the following command on all nodes: sudo /usr/bin/mysql_secure_installationI choose password as ‘dbpass’ and accepted all defaults (so answered yes to all questions). Step 5 – Create MariaDB Galera Cluster users Now, we have to create some users that must be able to access the database. The ‘sst_user’ is the user which a database node will use for authenticating to another database node in the State Transfer Snapshot (SST) phase. Run the following command on all nodes: mysql -u root -pmysql> DELETE FROM mysql.user WHERE user=''; mysql> GRANT ALL ON *.* TO 'root'@'%' IDENTIFIED BY '111111'; mysql> GRANT USAGE ON *.* to sst_user@'%' IDENTIFIED BY '111111'; mysql> GRANT ALL PRIVILEGES on *.* to sst_user@'%'; mysql> FLUSH PRIVILEGES; mysql> quitYou are suggested to change ‘%’ to hostname(s) or IP addresses from which those users can access the database. Because ‘%’ means that the root or sst_user is allowed to access the database from any host, So less security. Step 6 – Create the MariaDB Galera Cluster config First stop the mysql services on all nodes: sudo service mysql stopNext, We are going to create the MariaDB Galera Cluster configuration by the following command on all nodes (go through the IMPORTANT NOTE after the config and make required changes for db2, and db3): sudo cat >> /etc/my.cnf.d/server.cnf << EOFbinlog_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://1.1.1.1,1.1.1.2,1.1.1.3" wsrep_cluster_name='galera_cluster' wsrep_node_address='1.1.1.1' wsrep_node_name='db1' wsrep_sst_method=rsync wsrep_sst_auth=sst_user:dbpass EOFIMPORTANT NOTE: when executing this command on db2 and db3 do not forget to adjust thewsrep_node_address and wsrep_node_name variables. On db2 : wsrep_node_address=1.1.1.2 wsrep_node_name='db2'On db3 : wsrep_node_address='1.1.1.3' wsrep_node_name='db3'Step 7– Initialize the first cluster node Start MariaDB with the special ‘‐‐wsrep-new-cluster’ option , Do it on node db1 only so the primary node of the cluster is initialized: sudo /etc/init.d/mysql start --wsrep-new-clusterCheck status by run the following command on node db1 only: mysql-uroot-p-e"show status like 'wsrep%'"Some important information in the output are the following lines: wsrep_local_state_comment | Synced <-- cluster is synced wsrep_incoming_addresses | 1.1.1.1:3306 <-- node db1 is a provider wsrep_cluster_size | 1 <-- cluster consists of 1 node wsrep_ready | ON <-- good :)Step 8– Add the other cluster nodes Check and confirm nodes db2 and db3 have the correct configuration in /etc/my.cnf.d/server.cnf under the [mariadb-10.0] as described in step 6. With the correct configuration in place, all that is required to make db2 and db3 a member of the cluster is to start them like you would start any regular service. On db2 issue the following command: sudo service mysql startCheck what has changed in the cluster status by executing the following command on db1 or db2: mysql -u root -p -e "show status like 'wsrep%'"And you will see that node db2 is now known as the cluster size is ‘2’ and the IP address of node db2 is listed: | wsrep_local_state_comment | Synced | | wsrep_incoming_addre sses | 1.1.1.1:3306,1.1.1.2:3306 | | wsrep_cluster_size | 2 | | wsrep_connected | ON | | wsrep_ready | ON |Repeat the same step for node db3. On node db3 only execute the following command sudo service mysql startCheck what has changed in the cluster status by executing the following command on for example db1: mysql -u root -p -e "show status like 'wsrep%'"And you should see that node db3 is now known as the cluster size is ‘3’ and the IP address of node db3 is listed: | wsrep_local_state_comment | Synced | | wsrep_incoming_addresses | 1.1.1.3:3306,1.1.1.1:3306,1.1.1.2:3306 | | wsrep_cluster_size | 3 | | wsrep_connected | ON | | wsrep_ready | ON |Step 9 – Verify replication Now the cluster is running. Let’s test whether it is working. On db1 create a database ‘clustertest’ by run the following command: mysql -u root -p -e 'CREATE DATABASE clustertest;'mysql -u root -p -e 'CREATE TABLE clustertest.mycluster ( id INT NOT NULL AUTO_INCREMENT, name VARCHAR(50), ipaddress VARCHAR(20), PRIMARY KEY(id));'mysql -u root -p -e 'INSERT INTO clustertest.mycluster (name, ipaddress) VALUES ("db1", "1.1.1.1");'Check if the database, table and data exists: mysql -u root -p -e 'SELECT * FROM clustertest.mycluster;'Enter password: +----+------+-----------+ | id | name | ipaddress | +----+------+-----------+ | 2 | db1 | 1.1.1.1 | +----+------+-----------+Now do the check on node db2: mysql -u root -p -e 'SELECT * FROM clustertest.mycluster;'Enter password: +----+------+-----------+ | id | name | ipaddress | +----+------+-----------+ | 2 | db1 | 1.1.1.1 | +----+------+-----------+Now do the same check on node db3: mysql -u root -p -e 'SELECT * FROM clustertest.mycluster;'Enter password: +----+------+-----------+ | id | name | ipaddress | +----+------+-----------+ | 2 | db1 | 1.1.1.1 | +----+------+-----------+From these outputs we can confirm that everything was successfully replicated by node db1 across all other nodes. That’s it. Cheers! (责任编辑：IT) |