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Note: This is an RHCE 7 exam objective.

Presentation of MariaDB

MariaDB is a binary replacement for MySql, the famous database system.

Prerequisites

As the default MariaDB installation uses the /var/lib/mysql directory to store your databases, keep in mind that the partition or logical volume associated with /var needs adequate space.

Installation Procedure

To install it, apply the following steps:

Install the MariaDB packages:

# yum install -y mariadb mariadb-server

Start and activate at boot the MariaDB service:

# systemctl start mariadb && systemctl enable mariadb

Execute the basic setup:

# mysql_secure_installation
/usr/bin/mysql_secure_installation: line 379: find_mysql_client: command not found

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
SERVERS IN PRODUCTION USE! PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current
password for the root user. If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.

Enter current password for root (enter for none): type enter
OK, successfully used password, moving on...

Setting the root password ensures that nobody can log into the MariaDB
root user without the proper authorisation.

Set root password? [Y/n] Y
New password: your-password
Re-enter new password: your-password
Password updated successfully!
Reloading privilege tables..
... Success!

By default, a MariaDB installation has an anonymous user, allowing anyone
to log into MariaDB without having to have a user account created for
them. This is intended only for testing, and to make the installation
go a bit smoother. You should remove them before moving into a
production environment.

Remove anonymous users? [Y/n] Y
... Success!

Normally, root should only be allowed to connect from 'localhost'. This
ensures that someone cannot guess at the root password from the network.

Disallow root login remotely? [Y/n] Y
... Success!

By default, MariaDB comes with a database named 'test' that anyone can
access. This is also intended only for testing, and should be removed
before moving into a production environment.

Remove test database and access to it? [Y/n] Y
- Dropping test database...
... Success!
- Removing privileges on test database...
... Success!

Reloading the privilege tables will ensure that all changes made so far
will take effect immediately.

Reload privilege tables now? [Y/n] Y
... Success!

Cleaning up...

All done! If you've completed all of the above steps, your MariaDB
installation should now be secure.

Thanks for using MariaDB!

If you need to access the database from a different server, add the MySql service to the firewall configuration and reload it:

# firewall-cmd --permanent --add-service=mysql
success
# firewall-cmd --reload
success

The Centminmod website warns of MariaDB restart issues after RHEL 7.4/CentOS 7.4 upgrade.

Initial Configuration

To help you define the initial configuration according to the specifications of your system (memory size, number of CPU, type of activity, etc), you can find useful examples of my.cnf files in the mariadb-server package:

# rpm -ql mariadb-server | grep my-
/usr/share/mysql/my-huge.cnf
/usr/share/mysql/my-innodb-heavy-4G.cnf
/usr/share/mysql/my-large.cnf
/usr/share/mysql/my-medium.cnf
/usr/share/mysql/my-small.cnf

Start by reading the /usr/share/mysql/my-innodb-heavy-4G.cnf file because it is full of useful comments.

Then, download Major Hayden’s mysqltuner.pl. After running this script, you will get a rough evaluation of your configuration and basic recommentations to improve it.

The innotop package contains a command with the same name that behaves like the top command on MariaDB servers, providing a lot of details about the current activity (cache, locks, replication status, etc). This package is available in the EPEL repository.

Configuration Tip

To get an explanation of all the server options, all the configuration parameters and their current values, type:

# /usr/libexec/mysqld –verbose –help
/usr/libexec/mysqld  Ver 5.5.52-MariaDB for Linux on x86_64 (MariaDB Server)
Copyright (c) 2000, 2016, Oracle, MariaDB Corporation Ab and others.

Starts the MariaDB database server.

Usage: /usr/libexec/mysqld [OPTIONS]

Default options are read from the following files in the given order:
/etc/mysql/my.cnf /etc/my.cnf ~/.my.cnf 
The following groups are read: mysqld server mysqld-5.5 mariadb mariadb-5.5 client-server
The following options may be given as the first argument:
--print-defaults        Print the program argument list and exit.
--no-defaults           Don't read default options from any option file.
--defaults-file=#       Only read default options from the given file #.
--defaults-extra-file=# Read this file after the global files are read.

  --allow-suspicious-udfs 
                      Allows use of UDFs consisting of only one symbol xxx()
                      without corresponding xxx_init() or xxx_deinit(). That
                      also means that one can load any function from any
                      library, for example exit() from libc.so
  -a, --ansi          Use ANSI SQL syntax instead of MySQL syntax. This mode
                      will also set transaction isolation level 'serializable'.
  --archive[=name]    Enable or disable ARCHIVE plugin. Possible values are ON,
                      OFF, FORCE (don't start if the plugin fails to load).
...
  --xtradb-admin-command[=name] 
                      Enable or disable XTRADB_ADMIN_COMMAND plugin. Possible
                      values are ON, OFF, FORCE (don't start if the plugin
                      fails to load).

Variables (--variable-name=value)
and boolean options {FALSE|TRUE}                  Value (after reading options)
------------------------------------------------- ------------------------
allow-suspicious-udfs                             FALSE
archive                                           ON
aria                                              ON
aria-block-size                                   8192
aria-checkpoint-interval                          30
aria-checkpoint-log-activity                      1048576
aria-force-start-after-recovery-failures          0
aria-group-commit                                 none
...
verbose                                           TRUE
wait-timeout                                      28800
xtradb-admin-command                              ON

To see what values a running MySQL server is using, type
'mysqladmin variables' instead of 'mysqld --verbose --help'.

Additional Resources

Additional information about the transition from MySQL to MariaDB is available on Kolbe’s blog. Rackspace offers an interesting tutorial about installing and configuring a MySQL/MariaDB server. Carla Schroder’s blog provides some thought about which type of file system to choose and what are the best parameters to set performance-wise. A presentation about database performance tuning was given at the 2015 Red hat Summit (the associated slides are there). The linuxpitstop website provides some tips to improve MariaDB performance. If you are more interested in Oracle products, Red Hat wrote a document about Deploying Oracle RAC Database 12c on RHEL 7. You can also watch Andrew Mallett‘s video about Installing MariaDB (6min/2015). Ramesh Natarajan provides an interesting tutorial on How to Move your MySQL Data Directory to a New Location. The Digital Ocean website has got a tutorial on How to Change a MariaDB Data Directory to a New Location on CentOS 7. The askapache website offers a tutorial on how to compile MariaDB with LZ4 compression. You can also read this tutorial about configuring MariaDB SSL and securing client connections. The Tecmint website wrote an article about 15 Useful MySQL/MariaDB Performance Tuning and Optimization Tips. The Howtoforge website explains how to enable SSL and remote connections for MySQL on CentOS 7 and how to set up a MySQL multi-master replication. The Servercheap website provides a tutorial on how to setup remote and secure connections for MySQL on CentOS 7. Colin Charles gave a presentation at the CentOS Dojo Brussels 2018 about Understanding the MySQL Database ecosystem (48min/2018).

The Percona website provides many interesting articles about MariaDB:

The Percona website has got also many interesting articles about MySQL:

Also, the ScaleGrid blog provides some interesting articles about MySQL:

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