Patent ID: 9740427
Date: 2017-08-22
CPC Classifications: G06F

Claim:
1. A method of copying data in a virtual sequential access volume, comprising: a first computer receiving, from a host, first data and a byte write start position, wherein the first data comprises a set of bytes, within the virtual sequential access volume, spanning from the byte write start position to an ending byte position corresponding to an end of the virtual sequential access volume; the first computer writing the first data, beginning from the byte write start position, into a copy of the first virtual sequential access volume and storing the first copy in a first storage device; the first computer updating first version information, corresponding to the first copy, and storing in the first storage device the updated first version information and first information on the byte write start position; a second and a third computer receiving, in response to a demount operation of the host associated with the first computer completing writing the first data into the first copy, the byte write start position; in response to the second computer receiving the byte write start position, the second computer receiving the first data from the first computer, writing the first data, beginning from the byte write position, into a second copy of the virtual sequential access volume, and storing the second copy in a second storage device; the second computer updating second version information, corresponding to the second copy, and storing, in the second storage device, the updated second version information and second information on the byte write start position; in response to the third computer receiving the write start position, the third computer receiving the first data from one of the first computer and the second computer, writing the first data, beginning from the byte write start position, into a third copy of the virtual sequential access volume, and storing the third copy in a third storage device; and the third computer updating a third version information, corresponding to the third copy, and storing, in the third storage device, the updated third version information and third information on the byte write start position; wherein the method further comprises the second computer responding to an interruption of the second computer writing the first data into the second copy by: storing, in the second storage device, an interrupted byte position corresponding to a byte position, within the second copy, at which the writing the first data into the second copy was interrupted; requesting the first computer to transmit, to the second computer, second data corresponding to data, within the first data, spanning from the stored interrupted byte position to the ending byte position; and writing the second data, beginning from the stored interrupted byte position, into the second copy.