The Ultimate Guide to High Availability with MariaDB

MariaDB Backup Overview

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Contents

  1. About MariaDB Backup
  2. MariaDB Backup Releases
  3. Installing on Linux
  4. Installing on Windows
  5. Using MariaDB Backup
    1. Configuring MariaDB Backup
    2. Using MariaDB Backup for Galera SSTs
      1. Granting Privileges for SST's
  6. MyRocks Support in Mariabackup
  7. Versions
  8. Limitations
  9. Differences Compared to Percona XtraBackup
  10. Internal (How things works)
    1. Redo Log Files
  11. See Also

About MariaDB Backup

MariaDB Backup is an open source tool provided by MariaDB for performing physical online backups of InnoDB, Aria and MyISAM tables. For InnoDB, “hot online” backups are possible. MariaDB Backup is provided as part of MariaDB Server starting with MariaDB 10.1.23 and MariaDB 10.2.7. It reached GA status starting with MariaDB 10.1.26 and MariaDB 10.2.10. The tool is available on Linux and Windows.

MariaDB Server 10.1 introduced MariaDB Compression and Data-at-Rest Encryption. For both we have seen high interest from the users of MariaDB Server. However, existing backup solutions from our ecosystem did not support full backup capability for these features.

To address our customers and community users concerns, we decided to provide a backup solution that would support full backup capability for MariaDB Server that includes encrypted and compressed data. The most obvious way to do this was to create a solution based on the well known and used backup tool Percona XtraBackup (version 2.3.8). We extended it and named our solution MariaDB Backup.

MariaDB Backup Releases

The mariabackup executable is included in tar.gz and zip packages. DEB or RPM packages include it as a separate RPM/DEB. Mariabackup is available starting with MariaDB 10.1.23.

Installing on Linux

MariaDB Backup is a separate package in our repositories. On Debian and Ubuntu, it can be installed with (for 10.1):

sudo apt-get install mariadb-backup-10.1

On CentOS, and RHEL it can be installed with:

sudo yum install MariaDB-backup

On Fedora and SLES/OpenSUSE it can be installed by replacing yum in the example above with dnf and zypper, resepectively.

Installing on Windows

To install on Windows, select Backup utilities:

mariadb_backup_windows

Using MariaDB Backup

MariaDB Backup is based on Percona XtraBackup 2.3.8 and therefore provides similar functionality plus:

  • Backup/Restore of Data-at-Rest encrypted XtraDB/InnoDB tables.
  • Backup/Restore when MariaDB Compression is used for table types XtraDB/InnoDB.
  • Backup/Restore of Data-at-Rest encrypted Aria tables.
  • Using MariaDB Backup for a SST with Galera Cluster, when Data-at-Rest encryption is used.
  • Support of Microsoft Windows.

The command to use MariaDB Backup is

mariabackup <params>

Configuring MariaDB Backup

Since MariaDB Backup is based on Percona XtraBackup, it can be configured similarly. The username and password can be included in .cnf files:

[xtrabackup]
user=myuser
password=mypassword

Note that MariaDB Backup does not read options in the [mariadb] section of configuration files. Therefore, if a non-defult datadir is specified on a server, it must be specified in the [xtrabackup] or [mysqld] sections of configuration files for MariaDB Backup to be able to find the datadir and run correctly:

[mysqld]
datadir=/var/mycustomdatadir

The MariaDB backup user must have RELOAD, LOCK TABLES, and REPLICATION CLIENT privileges.

Using MariaDB Backup for Galera SSTs

In addition to the mariabackup utility, MariaDB Server installations also include the wsrep_sst_mariabackup shell script, which allows you to use MariaDB Backup to handle State Snapshot Transfers when the server operates as a node in Galera Cluster.

To use MariaDB Backup with SST's, you must set the wsrep_sst_method and wsrep_sst_auth system variables.

[mysqld]
...
wsrep_sst_method = mariabackup
wsrep_sst_auth = user:password

This tells the node that you want to use the wsrep_sst_mariabackup script for State Snapshot Transfers and provides the authentication information it needs to access the other nodes in the cluster.

During the SST process, the donor node streams the backup to the joiner node. Then the joiner node prepares the backup before restoring it. Both the backup and prepare steps require MariaDB Backup, so you need to have it installed on both hosts. In addition to MariaDB Backup, you also need to have socat installed on the host. MariaDB Backup uses this utility to stream the backup from donor to joiner. It is a limitation MariaDB Backup inherits from the Xtrabackup version 2 SST method.

To secure the SST transfer using TLS, see

Granting Privileges for SST's

The user set for the wsrep_sst_auth system variable need to have the RELOAD , PROCESS, LOCK TABLES and REPLICATION CLIENT privileges. You need to set these privileges for each node in your cluster on each node in your cluster. For instance, if your cluster has the IP addresses of 192.168.1.1, 192.168.1.2 and 192.168.1.3, on the first node you would run the following GRANT statements:

GRANT RELOAD, PROCESS, LOCK TABLES, REPLICATION CLIENT TO 'backup_user'@'192.168.1.2';

GRANT RELOAD, PROCESS, LOCK TABLES, REPLICATION CLIENT TO 'backup_user'@'192.168.1.3';

This grants the user backup_user access to the first node from the second and third nodes. You can then issue the same GRANT statements on the second and third node, substituting their own IP addresses for that of the first node, ensuring that the backup user is able to operate across the cluster.

MyRocks Support in Mariabackup

Starting with MariaDB 10.2.16 and MariaDB 10.3.8, Mariabackup will back up MyRocks Storage Engine data. Partial backup of MyRocks data is currently not supported. Incremental backup will store a full copy of MyRocks data.

Versions

MariaDB Backup/Server VersionMaturity
MariaDB 10.2.10+, MariaDB 10.1.26+Stable
MariaDB 10.2.7+, MariaDB 10.1.25Beta
MariaDB 10.1.23Alpha

Limitations

MariaDB until 10.2.8

Before MariaDB 10.2.9, MariaDB Backup did not support the --export functionality. In earlier versions, you can workaround this limitation by preparing the backup as usual (without the --export flag), then start the server and execute FLUSH TABLES FOR EXPORT.

Note that mariabackup until 10.2.8 doesn't create empty log files and relies on the --copy-back action executed by user (which deletes old innodb log files, if any).

For situations where users don't use --copy-back or make sure that the data directory is empty before restoring, backups created with mariabackup until 10.2.8 may well become inconsistent/corrupted (because of the presence of leftover InnoDB logs).

Limitations compared to Percona XtraBackup:

  • Backup tool based encryption (gcrypt) is not supported.
  • No symlink to innobackupex - use the “--innobackupex” parameter instead.
  • "--compact" and "--rebuild_indexes" are not supported
  • Support for --stream=tar was removed in 10.1.24

Differences Compared to Percona XtraBackup

  • mariabackup creates an invalid (empty) redo-log-file, ib_logfile0 as part of the prepare stage, to protect against wrong 'cp' commands. XtraBackup uses the file name xtrabackup_logfile.

Internal (How things works)

Redo Log Files

In MariaDB 10.2, the ib_logfile0 that is created in the prepare phase has 3 roles:

  1. in the source server, it is the first (possibly the only) redo log file.
  2. in the non-prepared backup, all the log is in ib_logfile0 (formerly called xtrabackup_logfile)
  3. after --prepare aka --apply-log the log file used to be deleted, but with MDEV-13311 we create a dummy ‘poison’ file. This is done to protect against someone could do a simple cp -r backup/* datadir where datadir/ib_logfile* already existed. Before MDEV-13311, there would be no backup/ib_logfile*, and the above cp command would create a situation where InnoDB can try to recover from mismatching ib_logfile*. With --copy-back this problem never existed. With MDEV-13311 we create a ‘poison’ file to prevent startup before the user fixes their script.

See Also

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