Patent ID: 9235349
Filing Date: 2016-01-12
CPC Classification: G06F

Claim Text:
1. A snapshot-type data duplication system, comprising: duplication volumes for a master volume; a shared pool volume which stores duplication data of the duplication volumes; and a main control unit which manages data accesses for the duplication data made from outside to the duplication volumes and manages a storing place of the duplication data, wherein: the main control unit comprises a data duplication control module which manages data accesses made from outside to the duplication volume, and an address changing module which manages the storing place of the duplication data; the data duplication control module includes a data duplication update processing function which duplicates data of the master volume to the duplication volume when updating the master volume, and performs an update to the data of the duplication volume without using an intermediary when updating the data of the duplication volume; the data duplication control module is provided with a data duplication control memory which comprises a difference managing table for storing that data duplication is executed from the master volume to the duplication volume and an update managing table for storing that update to the data duplication is performed to the duplication volume without using an intermediary; the address changing module is provided with an address changing control memory which comprises an allotment managing table for storing use state of the shared pool volume; the data duplication control module judges whether or not the update to the duplication volume without using the intermediary is already executed by referring to the update managing table stored in the data duplication control memory when updating the data of the duplication volume, writes data that corresponds to the write command to the address of the shared pool volume allotted in advance to the duplication volume when judged that there is an update in the duplication volume, searches a vacant region of the shared volume by referring to the allotment managing table when judged that there is no update in the duplication volume, writes data that corresponds to the write command, when the vacant region of the shared pool volume is found in a step of searching the vacant region, to the found vacant region, stores an address of the vacant region on the shared pool volume to which the data has been written to a prescribed memory as a reference target of the update data of the duplication volume, and registers data showing that there is update data in the duplication volume to a corresponding section of the update managing table, to execute the data duplication update processing function.