Patent ID: 6883112
Filing Date: 2005-04-19
Classification: G06F,Y10S

Abstract:
1. A storage device configured to allow fault-tolerant continuous input and output of data even during a data backup operation, comprising: a first storage unit having a first data storage capacity and configured to store data, and to continuously update the stored data; a second storage unit configured to store data to be backed up during the data backup operation and having a same data storage capacity as the data storage capacity of the first storage unit; a third storage unit configured to store update data received during the data backup operation, said third storage unit having a storage capacity smaller than that of said first storage unit; and a control unit configured to receive a data update request and to control data updating, wherein the control unit controls the data updating while no data backup operation is being performed by causing data to be updated in the first storage unit and in the second storage unit so that contents of the first and second storage units are equal, wherein the control unit controls the data updating during the data backup operation by causing data to be updated in only the first storage unit while the data backup operation is performed on the data stored in the second storage unit, and causing any update data received by the control unit to be stored in the third storage unit, wherein the control unit restores data stored in the first storage unit at a point of time when a failure occurs in the first storage unit during the backup operation based on data stored in the second storage unit combined with the update data stored in the third storage unit.