4.1.1 Collect Database Information

Before backing up a particular database server for the first time, gather some information and use it to make some planning decisions, as outlined in the following table.

Table 4.1 Information Needed to Back Up a Database

Information to Gather	Where to Find It	How Used
Path to MySQL configuration file	Default system locations, hardcoded application default locations, or from the --defaults-file option in the mysqld startup script.	This is the preferred way to convey database configuration information to mysqlbackup, using the --defaults-file option. When connection and data layout information is available from the configuration file, you can skip most of the other choices listed below.
MySQL port	MySQL configuration file or mysqld startup script.	Used to connect to the database instance during backup operations. Specified via the --port option of mysqlbackup. --port is not needed if available from MySQL configuration file. Not needed when doing a cold (offline) backup, which works directly on the files using OS-level file permissions.
Path to MySQL data directory	MySQL configuration file or mysqld startup script.	Used to retrieve files from the database instance during backup operations, and to copy files back to the database instance during restore operations. Automatically retrieved from database connection for hot and warm backups, and taken from MySQL configuration file for cold backups.
ID and password of privileged MySQL user	You record this during installation of your own databases, or get it from the DBA when backing up databases you do not own. Not needed when doing an offline (cold) backup, which works directly on the files using OS-level file permissions. For cold backups, you log in as an administrative user.	Specified via the --password option of the mysqlbackup. Prompted at the terminal if the --password option is present without the password argument.
Path under which to store backup data	You choose this. See Section 4.1.3, “Designate a Location for Backup Data” for details.	By default, this directory must be empty for mysqlbackup to write data into it, to avoid overwriting old backups or mixing up data from different backups. Use the --with-timestamp option to automatically create a subdirectory with a unique name, when storing multiple sets of backup data under the same main directory.
Owner and permission information for backed-up files (for Linux, Unix, and OS X systems)	In the MySQL data directory.	If you perform the backup and restore using a different OS user than the one who runs the server, this information might become important. See Section 4.2.1, “OS User for Running mysqlbackup” for details.
Size of InnoDB redo log files	Calculated from the values of the innodb_log_file_size and innodb_log_files_in_group configuration variables. Use the technique explained for the --incremental-with-redo-log-only option.	Only needed if you perform incremental backups using the --incremental-with-redo-log-only option rather than the --incremental option. The size of the InnoDB redo log and the rate of generation for redo data dictate how often you must perform incremental backups.
Rate at which redo data is generated	Calculated from the values of the InnoDB logical sequence number at different points in time. Use the technique explained for the --incremental-with-redo-log-only option.	Only needed if you perform incremental backups using the --incremental-with-redo-log-only option rather than the --incremental option. The size of the InnoDB redo log and the rate of generation for redo data dictate how often you must perform incremental backups.