Patent ID: 8725686

Claim:
A method carried out in a computer, for preparing, in a backup system, a referable backup data of data of a database which is maintained in a primary system, by using data update records of said database which are successively sent from said primary system, the method comprising: collectively rerunning, on a first backup data set provided additionally beyond the database maintained in the primary system, every data update indicated in each of update records, which are respectively followed by individual records indicating transaction commit for said data, where the update records were sent from said primary system to effect backup of the data of the database maintained in the primary system; maintaining: a second backup data set provided additionally beyond the database maintained in the primary system, which is a previous copy of the first backup data set; and a third backup data set which is a copy of the second backup data set and which is provided additionally beyond the database maintained in the primary system; copying differing data of the second backup data set, which are different from said first backup data set, into the third backup data set, prior to a switch of a referring target from the second backup data set over to the third backup data set; switching a referring target from the second backup data set over to the third backup data set; canceling individual data updates on the first backup data set, which have an uncommitted transaction status; copying said first backup data set to said second backup data set after the canceling operation is completed, to sync the second backup data set to the first backup data set; switching back the referring target from said third backup data set over to said second backup data set; and copying said second backup data set to said third backup data set, to sync the third backup data set to the second backup data set.