Deploy a Primary Server with MariaDB Community Server 10.3 on CentOS 8
This procedure provides instructions detailing the deployment of MariaDB Community Server 10.3 in a Primary/Replica Topology as the primary server. If you are using MariaDB Enterprise Server 10.3, see "Deploy Primary/Replica Topology".
MariaDB Replication is suited for transactional or OLTP workloads that require high availability (HA).
These instructions require 1 or more MariaDB Server nodes deployed as replica servers.
See the following resources for how to deploy a replica server:
MariaDB Community Server Components
These instructions detail the deployment of the following MariaDB Community Server components:
MariaDB Corporation provides a YUM package repository for CentOS Linux 8.
MariaDB Community Server does not require any additional software to operate as a node in MariaDB Replication.
Install on CentOS/RHEL (YUM)
Configure the YUM package repository.
To configure YUM package repositories:
$ sudo yum install wget
$ wget https://downloads.mariadb.com/MariaDB/mariadb_repo_setup
$ echo "fd3f41eefff54ce144c932100f9e0f9b1d181e0edd86a6f6b8f2a0212100c32c mariadb_repo_setup" \ | sha256sum -c -
$ chmod +x mariadb_repo_setup
$ sudo ./mariadb_repo_setup \ --mariadb-server-version="mariadb-10.3"
Install MariaDB Community Server and package dependencies:
$ sudo yum install MariaDB-server MariaDB-backup
Installation only loads MariaDB Community Server to the system. MariaDB Community Server requires configuration before the database server is ready for use.
MariaDB Community Server can be configured in the following ways:
If a system variable supports dynamic changes, then it can be set on-the-fly using the SET statement.
MariaDB's packages include several bundled configuration files. It is also possible to create custom configuration files.
On RHEL, CentOS, and SLES, MariaDB's packages bundle the following configuration files:
And on RHEL, CentOS, and SLES, custom configuration files from the following directories are read by default:
Mandatory options and system variables for a Primary Server include:
Set this option to enable the Binary Log.
Sets the numeric Server ID for this MariaDB Community Server. Must be unique in the deployment.
Useful system variables and options for MariaDB Community Server include:
Sets the path to the data directory. MariaDB Community Server writes data files to this directory, including tablespaces, logs, and schemas. Change it to use a non-standard location or to start the Server on a different data directory for testing.
Sets the local TCP/IP address on which MariaDB Community Server listens for incoming connections. Bind to 0.0.0.0 to make the Server accessible through any network interface.
Sets the port MariaDB Community Server listens on. Use this system variable to use a non-standard port or when running multiple Servers on the same host for testing.
Sets the maximum number of simultaneous connections MariaDB Community Server allows.
Sets how MariaDB Community Server handles threads for client connections.
Sets the file name for the error log.
Sets the amount of memory InnoDB reserves for the Buffer Pool.
Sets the size for each Redo Log file and innodb_log_files_in_group sets the number of Redo Log files used by InnoDB.
Sets the maximum number of I/O operations per second that InnoDB can use.
Useful system variables and options for a Primary Server include:
Sets Binary Log events as row-based, statement-based, or a mix of rows and statements.
Sets the numeric domain identifier to use in Global Transaction ID's.
Sets MariaDB Community Server to enforce global ordering for Global Transaction ID's.
Choose a configuration file in which to configure your system variables and options.
It is not recommended to make custom changes to one of the bundled configuration files. Instead, it is recommended to create a custom configuration file in one of the included directories. Configuration files in included directories are read in alphabetical order. If you want your custom configuration file to override the bundled configuration files, then it is a good idea to prefix the custom configuration file's name with a string that will be sorted last, such as
On RHEL, CentOS, and SLES, a good custom configuration file would be:
Set your system variables and options in the configuration file.
They need to be set in a group that will be read by mysqld, such as
[mariadb] # Server Configuration log_error = mariadbd.err innodb_buffer_pool_size = 1G # Replication Configuration (Primary Server) log_bin = mariadb-bin server_id = 1 binlog_format = ROW
Group commit can help performance by reducing I/O.
If you would like to configure parallel replication on the Replica, then it is also required to configure group commit on the Primary.
Sets the number of transactions that the server commits as a group to the binary log.
Sets the number of microseconds that the server waits for transactions to group commit before it commits the current group.
MariaDB Replication deployments that use MariaDB Community Server 10.2 have the option of enabling semi-synchronous replication for Primary Servers through the semisync_master plugin.
Configure the Replication User
Replica Servers replicate from the Primary Server through client connections. In order for them to access the Primary Server, the Replica Servers require a user account with sufficient privileges.
Connect to the Primary Server using MariaDB Client using the
$ sudo mysql
Create the user account with the CREATE USER statement:
CREATE USER repl@'%' IDENTIFIED BY 'repl_passwd';
Grant the user account the
REPLICATION SLAVEprivilege with the GRANT statement:
GRANT REPLICATION SLAVE ON *.* TO repl@'%';
When you have the Primary Server up and running, you should test that it is working and that there weren't any issues during startup. You should also ensure that the Server is correctly configured before starting replication on the Replica Servers.
Connect to the server using the MariaDB Client using the
$ sudo mysql
Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 38 Server version: 10.3.31-MariaDB MariaDB Server Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]>
Execute the SHOW MASTER STATUS statement to ensure that binary logging is enabled:
SHOW MASTER STATUS;
+--------------------+----------+--------------+------------------+ | File | Position | binlog_Do_DB | Binlog_Ignore_DB | +--------------------+----------+--------------+------------------+ | mariadb-bin.000003 | 4919 | | | +--------------------+----------+--------------+------------------+
The statement returns a result-set similar to the above when Binary Logging is enabled and you can move on to setting up the Replica Servers. An empty set means that Binary Logging is disabled and must be enabled before the Server can operate as a Primary Server.