Patent ID: 7325110

Claim:
A storage switch having a backup acquiring function and being connected to a host computer and a storage device, comprising: a means which mirrors contents of source data in a source volume as a snapshot target, thereby creating mirror data in the source volume containing the source data; wherein when creating a mirror of a file including data stored in storage areas that are distributed non-sequentially in the source volume, the mirror data are configured of storage areas of sequential data blocks in the source volume; a means which synchronizes the contents of the source data in the source volume, updated in response to an access request from the host computer, with contents of the mirror data in the source volume; a means which copies, in response to a snapshot creation command from a management computer, the contents of the mirror data from the source volume into a snapshot volume in parallel with writing of data into the source data in response to a write request thereto; and a means which records information items including a data start position in the source volume of the sequential data blocks of the mirror data to be copied from the source volume into the snapshot volume, a data start position in the snapshot volume as a copy destination for the contents of the mirror data to be copied from the source volume into the snapshot volume, and a data length in the source volume of the sequential data blocks of the mirror data to be copied from the source volume into the snapshot volume in a copy correspondence table, with a correspondence between the data start position in the source volume, the data start position in the snapshot volume, and the data length in the source volume of the sequential data blocks; wherein said means which copies the contents of the mirror data from the source volume into the snapshot volume in response to the snapshot creation command, refers to the CODV correspondence table to copy the contents of the mirror data beginning at the data start position in the source volume into the snapshot volume at the copy destination beginning at the data start position in the snapshot volume, the mirror data to be copied having the data length in the source volume recorded in the copy correspondence table.