Patent ID: 8438134

Claim:
A database copying system for making a copy of a database, the database copying system comprising: a first computer comprising: a mirroring unit to, when data is written on a plurality of local disks individually, write duplicate data of the data on remote disks in a same sequence as the data was written, the remote disks corresponding to the plurality of local disks, respectively; a current disk manager to select a first local disk out of the plurality of local disks as a current disk, and when stored data of the current disk reaches a maximum data capacity, switch the current disk to another local disk; a data writing unit to write the data on the current disk when a data writing request arrives; an operation information manager to, when the stored data of the current disk reaches the maximum data capacity, store first operation information in a second local disk selected out of the plurality of local disks, the first operation information requesting to update the copy of the database; and an operation information receiver to receive second operation information indicating completion of updating the copy of the database, wherein the current disk manager forbids the first local disk from being reselected as the current disk from the time when the current disk is switched to the other local disk to the time when the second operation information is received, and allows the first local disk to be reselected as the current disk after the second operation information is received; and a second computer comprising: a database update unit to, when the first operation information is copied from the second local disk to a second remote disk corresponding to the second local disk, update the copy of the database based on the duplicate data stored in a first remote disk corresponding to the first local disk; and a transmitter to transmit the second operation information to the first computer after updating the copy of the database is completed.