1.3.1 Types of Files Contained in a Backup

The following table shows the different types of files that are included in a single-file backup image or a directory backup. In the case of a single-file backup, unpack the file into a backup directory structure using the extract or the image-to-backup-dir command to view the files.

Table 1.1 Types of Files in a Backup

File Name, Pattern, or Extension	Relation to Original Data Files	Notes
ibdata*	The InnoDB system tablespace, containing multiple InnoDB tables and associated indexes.	Because the original files might change while the backup is in progress, the apply-log step applies the same changes to the corresponding backup files.
*.ibd	An InnoDB tablespace, which can be (a) a file-per-table tablespace, containing a single InnoDB table and associated indexes, or (b) a file-per-table external tablespace located outside of the server's data directory, containing a single InnoDB table and associated indexes, or (c) a general tablespace, containing one or more tables and their indexes.	Because the original files might change while the backup is in progress, the apply-log step applies the same changes to the corresponding backup files.
*.ibz	Compressed form of InnoDB data files from the MySQL data directory.	Produced instead of .ibd files in a compressed backup. The ibdata* files representing the InnoDB system tablespace also receive this extension in a compressed backup. The .ibz files are uncompressed during the apply-log, copy-back, or copy-back-and-apply-log step.
*.frm	Hold metadata about all MySQL tables.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.MYD	MyISAM table data.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.MYI	MyISAM index data.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.CSM	Metadata for CSV tables.	These files are copied unmodified. The backup_history and backup_progress tables created by mysqlbackup use the CSV format, so the backup always includes some files with this extension.
*.CSV	Data for CSV tables.	These files are copied unmodified. The backup_history and backup_progress tables created by mysqlbackup use the CSV format, so the backup always includes some files with this extension.
*.MRG	MERGE storage engine references to other tables.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.TRG	Trigger parameters.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.TRN	Trigger namespace information.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.opt	Database configuration information.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.par	Definitions for partitioned tables.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.ARM	ARCHIVE storage engine table metadata.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
*.ARZ	ARCHIVE storage engine table data.	The database is put into a read-only state while these files are copied. These files are copied unmodified.
backup-my.cnf	Records the configuration parameters that specify the layout and other important information about the MySQL data files.	The file is created during a backup, and it contains crucial parameters describing the backed-up data like innodb_data_file_path, innodb_log_file_size, innodb_log_files_in_group, and so on. It might also contain other InnoDB parameters like innodb_data_home_dir and innodb_undo_directory if some of the backup repository options were used during the backup. mysqlbackup uses the parameters stored in this file to understand the structure of the backup and to perform various operations. You might need to supply some of these parameters to mysqlbackup during a restore and to mysqld when you start the target server if the target server and the backup are configured differently. See the discussion in Section 4.2.4, “Restoring a Database” for details.
ibbackup_ibd_files	Records names of the .ibd files and their space IDs during an incremental backup.	This file is created during an incremental backup. During a restore, the information in the file is used to delete the tables from the full backup that has been removed between the time of the full backup and the time of the incremental backup.
ibbackup_logfile	A condensed version of the ib_logfile* files from the MySQL data directory.	The InnoDB log files (ib_logfile*) are fixed-size files that are continuously updated during the database's operation. For backup purposes, only the changes that are committed while the backup is in progress are needed. These changes are recorded in ibbackup_logfile, and used to re-create the ib_logfile* files during the apply-log phase.
ibbackup_redo_log_only	Created instead of the ibbackup_logfile for incremental backups taken with the --incremental-with-redo-log-only option.
ib_logfile*	Created in the backup directory by mysqlbackup during the apply-log phase after the initial backup.	These files are not copied from the original data directory, but rather re-created in the backup directory during the apply-log phase after the initial backup, using the changes recorded in the ibbackup_logfile file.
*.bl	Renamed version of each .isl file from the backed-up server.	A .isl file is created when you specify the location of an InnoDB table using the syntax CREATE TABLE ... DATA DIRECTORY = ... (see Creating Tables Externally for details) or when a table is put into a general tabelspace (only for MySQL 5.7 and after; see general tablespace for details). The .isl file acts like a symbolic link pointing to the tablespace file. The .bl files might or might not be turned back into .isl files during the copy-back or copy-back-and-apply-log operation. If the specified directory does not exist on the server where the backup is restored, mysqlbackup attempts to create it. If the directory cannot be created, the restore operation fails. Thus, if you would like to use the DATA DIRECTORY clause to put tables at different locations or to restore to a server with a different file structure where the corresponding directories cannot be created, edit the .bl files before restoring to point to directories that do exist on the destination server. When restoring a backup created with transportable tablespaces (TTS), if the directory on the target server pointed to by a .bl file already contains .ibd files, the --force option is required when you restore the backup.
Timestamped directory, such as 2011-05-26_13-42-02	Created by the --with-timestamp option. All the backup files go inside this subdirectory.	Use the --with-timestamp option to easily keep more than one set of backup data under the same main backup directory.
datadir directory	A subdirectory that stores the data files and database subdirectories from the original MySQL instance.	Created under the backup directory by mysqlbackup.
binary log files	Binary log files from the server, which are included in a backup by default (except when the backup is created with the --use-tts option). They allow a snapshot of the server to be taken, so a server can be cloned to its exact state. Using a full backup as a basis, the binary log files that are included with an incremental backup can be used for a point-in-time recovery (PITR), which restores a database to its state at a certain point in time after the last full backup. See Section 5.2, “Point-in-Time Recovery” for details.	Saved under the datadir directory inside the backup. A copy of the index file on the MySQL server that lists all the used binary log files, with the locations of the binary log files properly updated to point to the files' locations in the backup, is included into the backup as well also under the datadir directory. Use the --skip-binlog option to exclude the binary log from the backup. For offline backups, use the --log-bin-index option to specify the absolute path of the index file on the MySQL server that lists all the used binary log files, if it is different from the default value of the option, for mysqlbackup to find the binary log files and include them in the backups. For release 4.1.2 and later: By default, the binary log files and the index file are restored to the same locations they were found on the backed-up server. Use the --log-bin option to specify a different target location for the binary log. Use the --skip-binlog option to skip the restoring of the binary log. For release 4.1.1 and earlier: The binary log files and the index file are restored to the data directory of the restored server. Use the --skip-binlog option to skip the restoring of the binary log. The binary log files are compressed and saved with the .bz extension when being included in a compressed backup. Notes If any binary log files are missing on the server you are backing up, you should use the --skip-binlog option to avoid mysqlbackup throwing an error for the missing files. No binary log files are copied into the incremental backup if the --use-tts option or the --start-lsn option is used. To include binary log files for the period covered by the incremental backup, do not use the --use-tts option and, instead of --start-lsn, use the --incremental-base option, which provides the necessary information for mysqlbackup to ensure that no gap exists between binary log data included in the previous backup and the current incremental backup.
relay log files	Relay log files from a replica server, which are included in a backup of a replica server by default (except when the backup is created with the --use-tts option). Their inclusion saves the time and resources required for fetching the relay logs from the source when the replica is being restored.	Saved under the datadir directory under the backup directory. A copy of the index file on the replica server that lists all the used relay log files, with the locations of the relay log files properly updated to point to the files' locations in the backup directory, is included into the backup as well, under the datadir directory. Use the --skip-relaylog option to exclude the relay log from the backup. For offline backup, use the --relay-log-index option to specify the absolute path of the index file on the MySQL server that lists all the used relay log files, if it is different from the default value of the option, for mysqlbackup to find the relay log files and include them in the backups. For release 4.1.2 and later: By default, the relay log files and the index file are restored to the same locations they were found on the backed-up replica server. Use the --relay-log option to specify a different target location for the relay log. Use the --skip-relaylog option to skip the restoring of the relay log. For release 4.1.1 and earlier: The relay log files and the index file are restored to the data directory of the restored server. Use the --skip-relaylog option to skip the restoring of the relay log. The relay log files are compressed and saved with the .bz extension when being included in a compressed backup.
*.bz	Compressed binary log or relay log files.	The binary log and relay log files are compressed and saved with the .bz extension when being included in a compressed backup. They are decompressed during a restore.
*.bkt (for release 4.1.0, or release 4.1.1 and later working with MySQL 5.7.20 and earlier)	Transfer file created for an encrypted InnoDB table during backup .	It contains the reencrypted tablespace key and other information related to the encryption. See Chapter 6, Working with Encrypted InnoDB Tables for detail.
encrypted keyring data file (for release 4.1.1 and later working with MySLQ 5.7.21 and later)	For a server using the keyring_encrypted_file plugin, the file specified by the keyring_encrypted_file_data option on the server is copied over into the backup with its original name under the meta folder. For a server using the a keyring plugin other than keyring_encrypted_file, the file is named keyring_kef, saved under the meta folder.	An encrypted file containing the master key for InnoDB table encryption . See Chapter 6, Working with Encrypted InnoDB Tables for detail.
replication metadata repository files	Usually named master.info and relay-log.info, they are included by default in a backup of a replica database in a replication setup. See Replication Metadata Repositories, for details.	Saved under the datadir directory under the backup directory. For an offline backup, use the--master-info-file and --relaylog-info-file options to specify the absolute paths of the information files, if they are different from the default values of the options, for mysqlbackup to find those files and include them in the backups. The copying of these files are skipped during a backup or a restore when the --skip-relay-log option is used.
Backup image file	A single-file backup produced by the backup-to-image option, with a name specified by the --backup-image option.	You can move the image file without losing or damaging the contents inside it, then unpack it with mysqlbackup using the extract command and specifying the same image name with the --backup-image option. Although some extra files such as backup-my.cnf and the meta subdirectory are present in the backup directory, these files are also included in the image file and do not need to be moved along with it.
Any other files in subdirectories under the datadir directory (that is, under backup-dir/datadir/subdir)	Copied from the database subdirectories under the MySQL data directory.	By default, any unrecognized files in subdirectories under the MySQL data directory are copied to the backup. To omit such files, specify the --only-known-file-types option. Note Some limitations apply to this behavior. See the discussion here in Appendix B, Limitations of MySQL Enterprise Backup.
meta directory	A subdirectory that stores files with metadata about the backup.	Created under the backup directory by mysqlbackup. All files listed below go inside the meta subdirectory.
backup_variables.txt	Holds important information about the backup. For use by mysqlbackup only.	mysqlbackup consults and possibly updates this file during operations after the initial backup, such as the apply-log phase or the restore phase.
image_files.xml	Contains the list of all the files (except itself) that are present in the single-file backup produced by the backup-to-image or backup-dir-to-image options. For details about this file, see Section 13.4, “Using the MySQL Enterprise Backup Manifest”.	This file is not modified at any stage once generated.
backup_create.xml	Lists the command line arguments and environment in which the backup was created. For details about this file, see Section 13.4, “Using the MySQL Enterprise Backup Manifest”.	This file is not modified once it is created. You can prevent this file from being generated by specifying the --disable-manifest option.
backup_content.xml	Essential metadata for the files and database definitions of the backup data. It also contains details of all the plugins defined on the backed-up server, by which users should make sure the same plugins are defined in the same manner on the target server for restoration. For details about this file, see Section 13.4, “Using the MySQL Enterprise Backup Manifest”.	This file is not modified once created. You can prevent this file from being generated by specifying the --disable-manifest option.
comments.txt	Produced by the --comments or --comments-file option.	The comments are specified by you to document the purpose or special considerations for this backup job.
backup_gtid_executed.sql	Signifies the backup came from a server with GTIDs enabled.	GTIDs are a replication feature in MySQL 5.6 and higher. See Replication with Global Transaction Identifiers for details. When you back up a server with GTIDs enabled using mysqlbackup, the file named backup_gtid_executed.sql is created in the meta folder under the backup directory. Edit and execute this file after restoring the backup data on a replica server; see Section 7.1, “Setting Up a New Replica” for details.
server-my.cnf	Contains values of the backed-up server's global variables that are set to non-default values. Use this file or server-all.cnf to start the target server for restoration.	During a copy-back or copy-back-and-apply-log operation, the server repository options values (e.g., --datadir, --innodb_data_home_dir, etc.) in the file are modified if the command makes changes to them through the command options. However, during an apply-incremental-backup operation, the values already saved in the file take precedence and they are not modified by the option values supplied through the command. Warning When using the file to restart the target server, change parameters like --tmpdir, --general-log, etc., and any global variable that uses an absolute filepath to avoid the accidental usage of the wrong file locations by the target server.
server-all.cnf	Contains values of all the global variables of the backed-up server. Use this file or server-my.cnf to start the target server for restoration.	During a copy-back or copy-back-and-apply-log operation, the server repository options values (e.g., --datadir, --innodb_data_home_dir, etc.) in the file are modified if the command makes changes to them through the command options. However, during an apply-incremental-backup operation, the values already saved in the file take precedence and they are not modified by the option values supplied through the command. Warning When using the file to restart the target server, change parameters like --tmpdir, --general-log, etc., and any global variable that uses an absolute filepath to avoid the accidental usage of the wrong file locations by the target server.
ib_buffer_pool	The file produced on the server when innodb_buffer_pool_dump_at_shutdown (enabled by default on MySQL 5.7.7 and after) or innodb_buffer_pool_dump_now is enabled. It holds the list of tablespace IDs and page IDs of the server's buffer pool. The actual file name might be different, as it can be configured by the server's system variable innodb_buffer_pool_filename"	With the default setting on MySQL server 5.7.7 and after (innodb_buffer_pool_load_at_startup=ON), the target server, during start up, is going to restore the buffer pool state of the backed up server using this file. See Saving and Restoring the Buffer Pool State for details.