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. If the data directory is not empty, you have to use the --force option to allow overwriting of the old data, or mysqlbackup will error out.

• 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 13.3, “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, or you might have problem starting the restored server afterwards):

  • innodb_data_file_path

  • innodb_log_file_size

  • innodb_log_files_in_group

  • innodb_page_size

  • innodb_checksum_algorithm

  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, and innodb_log_files_in_group), 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/backup-tmp copy-back-and-apply-log

MySQL Enterprise Backup version 3.12.3 Linux-2.6.18-274.el5-i686 [2014/11/12] 
Copyright (c) 2003, 2014, Oracle and/or its affiliates. All Rights Reserved.

 mysqlbackup: 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/backup-tmp copy-back-and-apply-log 

 mysqlbackup: 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!".

 mysqlbackup: INFO: Backup Image MEB version string: 3.12.3 [2014/11/12]
141204 13:10:39 mysqlbackup: INFO: MEB logfile created at /home/admin/backup-tmp/meta/MEB_2014-12-04.13-10-39_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_page_size = 16384
  innodb_checksum_algorithm = innodb

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

 mysqlbackup: INFO: Creating 14 buffers each of size 16777216.
141204 13:10:39 mysqlbackup: INFO: Copy-back-and-apply-log operation starts with following threads
		1 read-threads    6 process-threads    1 write-threads
141204 13:10:39 mysqlbackup: INFO: Copying database directory: meta
141204 13:10:39 mysqlbackup: INFO: Copying datadir/ibdata1.
141204 13:10:39 mysqlbackup: INFO: Copying datadir/mysql/innodb_index_stats.ibd.
141204 13:10:39 mysqlbackup: INFO: Copying datadir/mysql/innodb_table_stats.ibd.
141204 13:10:39 mysqlbackup: INFO: Copying datadir/mysql/slave_master_info.ibd.
141204 13:10:39 mysqlbackup: INFO: Copying datadir/mysql/slave_relay_log_info.ibd.
141204 13:10:39 mysqlbackup: INFO: Copying database directory: datadir/mysql
141204 13:10:39 mysqlbackup: INFO: Copying datadir/mysql/slave_worker_info.ibd.
141204 13:10:39 mysqlbackup: INFO: Copying datadir/test2/tb1.ibd.
141204 13:10:39 mysqlbackup: INFO: Copying database directory: datadir/performance_schema
141204 13:10:39 mysqlbackup: INFO: Copying database directory: datadir/test
141204 13:10:39 mysqlbackup: INFO: Copying database directory: datadir/test2
141204 13:10:40 mysqlbackup: INFO: Copying database directory: datadir/mysql
141204 13:10:41 mysqlbackup: INFO: Copying database directory: datadir/performance_schema
141204 13:10:42 mysqlbackup: INFO: Copying database directory: datadir/test
141204 13:10:42 mysqlbackup: INFO: Copying database directory: datadir/test2
141204 13:10:43 mysqlbackup: INFO: Total files as specified in image: 161
141204 13:10:43 mysqlbackup: INFO: Creating server config files server-my.cnf and server-all.cnf in /var/lib/mysql
141204 13:10:43 mysqlbackup: INFO: Copy-back operation completed successfully.
 mysqlbackup: INFO: Source Image Path = /home/admin/backups/my.mbi


 mysqlbackup: INFO: Creating 14 buffers each of size 65536.
141204 13:10:43 mysqlbackup: INFO: Apply-log operation starts with following threads
		1 read-threads    1 process-threads
 mysqlbackup: INFO: Using up to 100 MB of memory.
141204 13:10:43 mysqlbackup: INFO: ibbackup_logfile's creation parameters:
          start lsn 1631744, end lsn 1631766,
          start checkpoint 1631766.
InnoDB: Doing recovery: scanned up to log sequence number 1631766
 mysqlbackup: 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 
 mysqlbackup: INFO: InnoDB: Setting log file size to 50331648
 mysqlbackup: INFO: InnoDB: Setting log file size to 50331648
141204 13:10:44 mysqlbackup: INFO: We were able to parse ibbackup_logfile up to
          lsn 1631766.
 mysqlbackup: INFO: Last MySQL binlog file position 0 120, file name mysqld-bin.000004:120
141204 13:10:44 mysqlbackup: INFO: The first data file is '/var/lib/mysql/ibdata1'
          and the new created log files are at '/var/lib/mysql'
141204 13:10:44 mysqlbackup: INFO: Apply-log operation completed successfully.
141204 13:10:44 mysqlbackup: INFO: Full Backup has been restored successfully.

mysqlbackup completed OK!

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 5.2, “Performing a Restore Operation”.