Online Backup was introduced in MySQL 6.0. Apart from performing the usual backup tasks the new feature is that it does not block the concurrent connection to the data base. Hense the world "Online", which means without blocking the database. Therefore, unlike other database backup solutions like mysql dump, which caused other transactions on the database to hang while the backup was being performed, the Online Backup allows Database Manipulation Language (DML) statements to execute concurrently while the backup is in progress. Though some locking of the database still happens. This locking is of Data Definition Language (DDL) statements like CREATE, ALTER or DROP queries, which means that only DML queries can execute concurrently while database backup is in progress. Thus, the backup of the database can be carried without losing any transaction activity that might be happening during that moment. For DBAs this could be an interesting feature to opt for with the MySQL 6.0 Server when its final build is released.