Full Backup and Restore with Mariabackup

When using Mariabackup, you have the option of performing a full or an
incremental backup. Full backups create a complete backup of the database
server in an empty directory while incremental backups update a previous
backup with whatever changes to the data have occurred since the backup.
This page documents how to perform full backups.


Backing up the Database Server

In order to back up the database, you need to run Mariabackup with the -
-backup option to tell it to perform a backup and with the --target-dir
option to tell it where to place the backup files. When taking a full
backup, the target directory must be empty or it must not exist.

To take a backup, run the following command:

$ mariabackup --backup \
   --target-dir=/var/mariadb/backup/ \
   --user=mariabackup --password=mypassword

The time the backup takes depends on the size of the databases or tables
you're backing up. You can cancel the backup if you need to, as the backup
process does not modify the database.

Mariabackup writes the backup files the target directory. If the target
directory doesn't exist, then it creates it. If the target directory exists
and contains files, then it raises an error and aborts.

Here is an example backup directory:

$ ls /var/mariadb/backup/

aria_log.0000001  mysql                   xtrabackup_checkpoints
aria_log_control  performance_schema      xtrabackup_info
backup-my.cnf     test                    xtrabackup_logfile
ibdata1           xtrabackup_binlog_info



Preparing the Backup for Restoration

The data files that Mariabackup creates in the target directory are not
point-in-time consistent, given that the data files are copied at different
times during the backup operation. If you try to restore from these files,
InnoDB notices the inconsistencies and crashes to protect you from
corruption

Before you can restore from a backup, you first need to prepare it to make
the data files consistent. You can do so with the --prepare option.

$ mariabackup --prepare \
   --target-dir=/var/mariadb/backup/



Restoring the Backup

Once the backup is complete and you have prepared the backup for restoration
(previous step), you can restore the backup using either the --copy-back or
the --move-back options. The --copy-back option allows you to keep the
original backup files. The --move-back option actually moves the backup
files to the datadir, so the original backup files are lost.

First, stop the MariaDB Server process. 

Then, ensure that the datadir is empty. 

Then, run Mariabackup with one of the options mentioned above: 

$ mariabackup --copy-back \
   --target-dir=/var/mariadb/backup/

Then, you may need to fix the file permissions. 
When Mariabackup restores a database, it preserves the file and directory
privileges of the backup. However, it writes the files to disk as the user
and group restoring the database. As such, after restoring a backup, you may
need to adjust the owner of the data directory to match the user and group
for the MariaDB Server, typically mysql for both. For example, to
recursively change ownership of the files to the mysql user and group, you
could execute:

$ chown -R mysql:mysql /var/lib/mysql/

Finally, start the MariaDB Server process. 




Restoring with Other Tools

Once a full backup is prepared, it is a fully functional MariaDB data
directory. Therefore, as long as the MariaDB Server process is stopped on
the target server, you can technically restore the backup using any file
copying tool, such as cp or rysnc. For example, you could also execute the
following to restore the backup:

$ rsync -avrP /var/mariadb/backup /var/lib/mysql/
$ chown -R mysql:mysql /var/lib/mysql/
$ rm /var/lib/mysql/ib_logfile*

When using Mariabackup from versions prior to MariaDB 10.2.10, you would
also have to remove any pre-existing InnoDB redo log files. For example:

$ rm /var/lib/mysql/ib_logfile*

See Mariabackup Internal Details: Redo Log Files for more information.