A SYSTEM FOR TAKING BACKUP IN A DATA BASE

摘要

For backing up in a distributed real time data base on primary memory in operation, all data in the data base are structured as belonging to one of several logic data bases, a logic data base being able to, but need not extend over several processors. A backup function of a certain logic data base is activated by sending a message to a central backup handler, which has information regarding processors, over which the current backup system extends, and synchronizes the backup function over processor borders. The synchronization includes that local data base handlers are informed that backup will be started and that a new transaction log is being created, in which all transactions having not attained commit state and which shall therefore not be included in the backup are logged. The backup will thereafter only contain changes of transactions in the old transaction log.