4.2.3 Restoring a Database

To restore a MySQL instance from a backup to a database server:

Shut down the database server.
Delete all files inside the server's data directory. Also delete all files inside the directories specified by the --innodb_data_home_dir, --innodb_log_group_home_dir, and --innodb_undo_directory options for restore, if the directories are different from the data directory.
Use, for example, the copy-back-and-apply-log command, which converts the raw backup into a prepared backup by updating it to a consistent state, and then copies the tables, indexes, metadata, and any other required files onto a target server. For the various options that you can specify for this operation, see Section 15.3, “Restore Operations”.

In the example below, the single-file backup created in the example given in Section 4.2.1, “Backing Up an Entire MySQL Instance” is restored using the copy-back-and-apply-log command. Besides the usual connection parameters, the following options are used:

--defaults-file supplies the configuration for restoring the data. It must be the first option to appear in a mysqlbackup command, if ever used. In most cases, you can supply to mysqlbackup with this option the configuration file for the target server to which you are restoring the data. However, when the following InnoDB settings for the backup are different from those on the target server, it is important to supply the values for the backup to mysqlbackup during restore and to mysqld when you start the restored server (otherwise, the restore might fail, and you might have problem starting the restored server):
If you are not sure about those settings for your backup, they are stored in the backup-my.cnf file during the backup—you can find the file either in the temporary directory you specified with --backup-dir when you created the single-image backup, or in a backup directory you can create by unpacking the backup image using the extract command. If the values of these options differ from those on the target server, add them to the configuration file you are supplying to mysqlbackup and also to the configuration file you are going to use to start the server afterwards; alternatively, you can also supply them as command line options to mysqlbackup and mysqld.
For some of the options listed above (namely, innodb_data_file_path, innodb_log_file_size, innodb_log_files_in_group, and innodb_undo_tablespaces), mysqlbackup checks the values you supply for them to ensure that you will be able to start the target server afterwards with those values: it throws an error if any of them does not match with the actual values for the backup. Warnings are given if those values are not specified for mysqlbackup in either the configuration file or on the command line (which is the case in the example below).
--datadir supplies the location of the data directory for restoring the data. You must specify this option for any restore operation.
--backup-image provides the path of the single-file backup.
--backup-dir provides the location of an empty folder to store some temporary files created during the restore procedure.

 
$ ./mysqlbackup  --defaults-file=/etc/mysql/my.cnf --datadir=/var/lib/mysql  \
   --backup-image=/home/admin/backups/my.mbi --backup-dir=/home/admin/restore-tmp copy-back-and-apply-log
MySQL Enterprise Backup version 4.1.0 Linux-2.6.39-400.215.10.el5uek-x86_64 [2017/02/13] 
Copyright (c) 2003, 2017, Oracle and/or its affiliates. All Rights Reserved.

170214 22:11:38 MAIN    INFO: A thread created with Id '140027243398976' 
170214 22:11:38 MAIN    INFO: Starting with following command line ...
 ./mysqlbackup --defaults-file=/etc/mysql/my.cnf --datadir=/var/lib/mysql 
        --backup-image=/home/admin/backups/my.mbi 
        --backup-dir=/home/admin/restore-tmp copy-back-and-apply-log 

170214 22:11:38 MAIN    INFO: 
IMPORTANT: Please check that mysqlbackup run completes successfully.
           At the end of a successful 'copy-back-and-apply-log' run mysqlbackup
           prints "mysqlbackup completed OK!".

170214 22:11:38 MAIN    INFO: Backup Image MEB version string: 4.1.0 [2017/02/13]
170214 22:11:38 MAIN    INFO: MySQL server version is '5.7.17'
170214 22:11:38 MAIN WARNING: If you restore to a server of a different version, the innodb_data_file_path parameter might have a different default. In 
that case you need to add 'innodb_data_file_path=ibdata1:12M:autoextend' to the target server configuration.
170214 22:11:38 MAIN WARNING: If you restore to a server of a different version, the innodb_log_files_in_group parameter might have a different default. 
In that case you need to add 'innodb_log_files_in_group=2' to the target server configuration.
170214 22:11:38 MAIN WARNING: If you restore to a server of a different version, the innodb_log_file_size parameter might have a different default. In th
at case you need to add 'innodb_log_file_size=50331648' to the target server configuration.
170214 22:11:38 MAIN    INFO: Keyring service not initialized. MEB cannot validate the encryption keys.
170214 22:11:38 MAIN    INFO: Valid keyring to be specified on server start to access the encrypted tables.
170214 22:11:38 MAIN    INFO: MEB logfile created at /home/admin/restore-tmp/meta/MEB_2017-02-14.22-11-38_copy_back_img_to_datadir.log

--------------------------------------------------------------------
                       Server Repository Options:
--------------------------------------------------------------------
  datadir                        = /var/lib/mysql
  innodb_data_home_dir           = /var/lib/mysql
  innodb_data_file_path          = ibdata1:12M:autoextend
  innodb_log_group_home_dir      = /var/lib/mysql
  innodb_log_files_in_group      = 2
  innodb_log_file_size           = 50331648
  innodb_buffer_pool_filename    = ib_buffer_pool
  innodb_page_size               = Null
  innodb_checksum_algorithm      = crc32

--------------------------------------------------------------------
                       Backup Config Options:
--------------------------------------------------------------------
  datadir                        = /home/admin/restore-tmp/datadir
  innodb_data_home_dir           = /home/admin/restore-tmp/datadir
  innodb_data_file_path          = ibdata1:12M:autoextend
  innodb_log_group_home_dir      = /home/admin/restore-tmp/datadir
  innodb_log_files_in_group      = 2
  innodb_log_file_size           = 50331648
  innodb_buffer_pool_filename    = ib_buffer_pool
  innodb_page_size               = 16384
  innodb_checksum_algorithm      = crc32

170214 22:11:38 MAIN    INFO: Creating 14 buffers each of size 16777216.
170214 22:11:38 MAIN    INFO: Copy-back-and-apply-log operation starts with following threads
		1 read-threads    6 process-threads    1 write-threads
170214 22:11:38 RDR1    INFO: A thread created with Id '140026981721856' 
170214 22:11:38 PCR1    INFO: A thread created with Id '140026973329152' 
170214 22:11:38 PCR1    INFO: Copying database directory: meta
170214 22:11:38 PCR2    INFO: A thread created with Id '140026964936448' 
170214 22:11:38 PCR3    INFO: A thread created with Id '140026956543744' 
170214 22:11:38 PCR4    INFO: A thread created with Id '140026948151040' 
170214 22:11:38 PCR5    INFO: A thread created with Id '140026939758336' 
170214 22:11:38 PCR6    INFO: A thread created with Id '140026931365632' 
170214 22:11:38 WTR1    INFO: A thread created with Id '140026922972928' 
170214 22:11:38 RDR1    INFO: Copying ibdata1.
170214 22:11:38 RDR1    INFO: Copying mysql/engine_cost.ibd.
170214 22:11:38 RDR1    INFO: Copying mysql/gtid_executed.ibd.
170214 22:11:38 RDR1    INFO: Copying mysql/help_category.ibd.
170214 22:11:38 RDR1    INFO: Copying mysql/help_keyword.ibd.
170214 22:11:38 RDR1    INFO: Copying mysql/help_relation.ibd.
170214 22:11:38 RDR1    INFO: Copying mysql/help_topic.ibd.
170214 22:11:38 PCR2    INFO: Copying database directory: mysql
170214 22:11:39 RDR1    INFO: Copying mysql/innodb_index_stats.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/innodb_table_stats.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/plugin.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/server_cost.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/servers.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/slave_master_info.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/slave_relay_log_info.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/slave_worker_info.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/time_zone.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/time_zone_leap_second.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/time_zone_name.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/time_zone_transition.ibd.
170214 22:11:39 RDR1    INFO: Copying mysql/time_zone_transition_type.ibd.
170214 22:11:40 PCR5    INFO: Copying database directory: performance_schema
170214 22:11:40 PCR5    INFO: Copying database directory: pets
170214 22:11:40 RDR1    INFO: Copying pets/cats.ibd.
170214 22:11:40 PCR5    INFO: Copying database directory: sys
170214 22:11:40 RDR1    INFO: Copying sys/sys_config.ibd.
170214 22:11:40 PCR5    INFO: Copying database directory: mysql
170214 22:11:40 PCR5    INFO: Copying database directory: performance_schema
170214 22:11:40 PCR5    INFO: Copying database directory: pets
170214 22:11:40 PCR5    INFO: Copying database directory: sys
170214 22:11:40 MAIN    INFO: Total files as specified in image: 297
170214 22:11:40 MAIN    INFO: MySQL server version is '5.7.17'
170214 22:11:40 MAIN    INFO: MySQL server compile os version is 'Linux'
170214 22:11:40 MAIN    INFO: Writing config file for server '5.7.17'.
170214 22:11:40 MAIN    INFO: Creating server config files server-my.cnf and server-all.cnf in /var/lib/mysql

[Some lines of output not shown]

170214 22:11:40 MAIN    INFO: Copy-back operation completed successfully.
170214 22:11:40 MAIN    INFO: Source Image Path = /home/admin/backups/my.mbi


170214 22:11:40 MAIN    INFO: MySQL server version is '5.7.17'
170214 22:11:40 MAIN    INFO: Restoring ...5.7.17 version
170214 22:11:40 MAIN    INFO: Creating 14 buffers each of size 65536.
170214 22:11:40 MAIN    INFO: Apply-log operation starts with following threads
		1 read-threads    1 process-threads    6 apply-threads
170214 22:11:40 MAIN    INFO: Using up to 100 MB of memory.
170214 22:11:40 MAIN    INFO: ibbackup_logfile's creation parameters:
          start lsn 2543104, end lsn 2543132,
          start checkpoint 2543123.
170214 22:11:40 ALW1    INFO: A thread created with Id '140026922972928' 
170214 22:11:40 ALW6    INFO: A thread created with Id '140027204466432' 
170214 22:11:40 ALW5    INFO: A thread created with Id '140027212859136' 
170214 22:11:40 ALW4    INFO: A thread created with Id '140026948151040' 
170214 22:11:40 ALW3    INFO: A thread created with Id '140026939758336' 
170214 22:11:40 ALW2    INFO: A thread created with Id '140026931365632' 
170214 22:11:40 RDR1    INFO: A thread created with Id '140027196073728' 
170214 22:11:40 PCR1    INFO: A thread created with Id '140027187681024' 
170214 22:11:40 PCR1    INFO: InnoDB: Doing recovery: scanned up to log sequence number 2543132.
170214 22:11:40 PCR1    INFO: InnoDB: Starting an apply batch of log records to the database...
.
InnoDB: Progress in percent: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 
 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 
 94 95 96 97 98 99 
170214 22:11:40 PCR1    INFO: InnoDB: Setting log file size to 50331648.
170214 22:11:45 PCR1    INFO: InnoDB: Setting log file size to 50331648.
170214 22:11:50 PCR1    INFO: We were able to parse ibbackup_logfile up to
          lsn 2543132.
170214 22:11:50 PCR1    INFO: The first data file is '/var/lib/mysql/ibdata1'
                              and the new created log files are at '/var/lib/mysql'
170214 22:11:50 MAIN    INFO: MySQL server version is '5.7.17'
170214 22:11:50 MAIN    INFO: Restoring ...5.7.17 version
170214 22:11:50 MAIN    INFO: Apply-log operation completed successfully.
170214 22:11:50 MAIN    INFO: Full Backup has been restored successfully.

mysqlbackup completed OK! with 3 warnings

Now the original database directory is restored from the backup. Depending on how you are going to start the restored server, you might need to adjust the ownership of the restored data directory. For example, if the server is going to be started by the user mysql, use the following command to change the owner attribute of the data directory and the files under it to the mysql user, and the group attribute to the mysql group.

$ chown -R mysql:mysql /path/to/datadir

You are now ready to start the restored database server. For more discussions on how to perform different kinds of restores, see Section 5.1, “Performing a Restore Operation”.