A method, computer program product, and a computer system, to store information related to changed data in response to a transaction with a first database of the on-line system requested during a planned period and data in the first database changed by the transaction. In response to a planned event a back-up system with a second database is switched to set up a new connection and a new transaction with the second database, wherein the second database is backup of the first database. The on-line system prevents setting up a new connection to the on-line system and prevents conducting a new transaction with the first database, sends information related to the changed data from the on-line system to the back-up system, and switches to the back-up system for a new connection and for a new transaction. The on-line system synchronizes data between the first database and the second database.