From The Open Source Backup Wiki (Amanda, MySQL Backup, BackupPC)
Using a single set of parameters to backup all of the MySQL databases results in poor performance. Either the backup takes too much time (backup window is too large and end users complain) or the backup size is too large/ too small for proper restoration.
To allow optimization of backups, ZRM for MySQL uses the concept of "backup sets". A backup set groups a set of databases or tables in a database that have to be backed up in the same manner and in one backup schedule. Each backup set is identified by a unique name (a string) for each MySQL ZRM instance.
Parameters which are common to all the database, or which are to be overwritten in only a handful of cases, are stored in the Global configuration file, mysql-zrm.conf.
Parameters that need to be different, or are specific for a backup set, are written in the backup set specific configuration file.
If any of the parameters that are specified in either the global configuration file or the backup set specific configuration file need to be overridden for one particular backup run, they can be specified on the command line directly.
In case of conflict, parameters in the backup set configuration file over-ride those in the Global configuration file. Further parameters specified on the command line over-ride all other parameters.
To ease the set up burden on the database administrator, ZRM for MySQL, resorts to default values when parameters are not specified. Default values are values that are assumed by ZRM for MySQL.
Use of Multiple Backup Sets
- It is advisable to create multiple backup sets based on the applications using the MySQL database and the time window available to do backups. All databases and/or tables in a database used by a single application should be part of one backup set.
- What is part of a backup-set is defined by the user of ZRM for MySQL. The user can specify what is part of a particular backup-set by specifying either the databases option or the database option and the tables option.
- Each backup set can have different MySQL server parameters and databases/tables to be backed up.
- All backup sets can share the same backup target directory.