Patent ID: 7464236
Filing Date: 2008-12-09
Classification: G06F,Y10S

Abstract:
1. A storage system in which a second storage control device and a third storage control device are connected to a first storage control device, wherein the first storage control device comprises a first data volume, a first journal volume for managing the update history of the first data volume, and a first control unit which sets a management number for write data and generates journal data when an upper-level device writes the write data into the first data volume, stores the journal data in the first journal volume, associates the management number with the write data to be transmitted to the second storage control device, the second storage control device comprises a second data volume related with the first data volume and a second control unit which stores the write data received from the first control unit in the second data volume, associates the management number received from the first control unit with a storage position in the second data volume of the write data to be stored in an update management table, the third storage control device comprises a third data volume related with the first data volume, a second journal volume related with the first journal volume, and a third control unit which reads the journal data from the first journal volume and stores the journal data in the second journal volume and updates the storage contents of the third data volume based on the journal data stored in the second journal volume, when a copy pair is formed by taking the second data volume as a primary volume and the third data volume as a secondary volume, the second control unit notifies the upper-level device to the effect that switching from the first storage control device to the second storage control device has been completed, and in the case of switching from the first storage control device to the second storage control device, the second control unit transmits to the third control unit the management number following the newest management number that is held in the third control unit and write data corresponding to the storage control device number.