A data backup method of a computer system, which comprises a primary storage apparatus and a secondary storage apparatus,
- wherein the primary storage apparatus comprises a first primary volume to and from which a host apparatus reads and writes data and a first secondary volume configured as a copy pair to the first primary volume, and
- wherein the secondary storage apparatus comprises a second primary volume configured as a remote-copy copy pair to the first primary volume and a second secondary volume which is configured as a copy pair to the second primary volume,
- the data backup method comprising:
- upon receiving a first copy instruction designating a first copy target area in the first primary volume from the host apparatus, using the primary storage apparatus to copy data in the first copy target area to the first secondary volume as a first intra-enclosure copy processing and to transmit a second copy instruction designating a second copy target area, which is related to the first copy target area, in the second primary volume;
- upon receiving the second copy instruction from the primary storage apparatus, using the secondary storage apparatus to copy data in the second copy target area to the second secondary volume as a second intra-enclosure copy processing;
- during the first intra-enclosure copy processing, upon receiving a first write request with write target data from the host apparatus designating a first storage area included in the first copy target area in the first primary volume, using the primary storage apparatus to transmit an advance notification designating a second storage area, which is related to the first storage area, in the second primary volume to the secondary storage apparatus before copying data stored in the first storage area to the first secondary volume;
- and
- to copy the data stored in the first storage area to the first secondary volume;
- upon receiving the advance notification from the primary storage apparatus, when data stored in the second storage area designated by the advance notification in the second primary volume have not been copied to the second secondary volume, using the secondary storage apparatus to copy the data stored in the second storage area to the second secondary volume while the primary storage apparatus copies the data stored in the first storage area to the first secondary volume;
- after copying the data stored in the first storage area to the first secondary volume, using the primary storage apparatus to write the write target data to the first storage area in the first primary volume designated in the first write request, and to transmit the write target data and a second write request designating the second storage area in the second primary volume corresponding to the first storage area to the secondary storage apparatus;
- and
- upon receiving the second write request from the primary storage apparatus,using the secondary storage apparatus to write the write target data to the second storage area designated in the second write request in the second primary volume.