Backing-up apparatus, backing-up method, and backing-up program

A backing-up method that produces, for each time point at which backing up is executed, a snapshot representing original data at a time point at which the backing up is executed for the original data to be backed up, the method comprising:

• allocating, upon receiving an instruction to execute the backing up, a storage area to store a snapshot produced at a time point designated by the instruction with respect to each time point designated by the instruction;
• checking, when original data is updated after the time point designated by the instruction, whether the original data corresponding to a place for which the updating has been executed at a time point immediately before the time point designated by the instruction is stored in the storage area allocated as a storage area to store the latest snapshot produced for the immediately previous time point;
• and
• storing, upon confirming that the original data is not stored, the original data immediately before the updating corresponding to the place for which the updating has been executed in only the storage area to store the latest snapshot.

A computer program product that produces, for each time point at which backing up is executed, a snapshot representing original data at the time point at which the backing up is executed for the original data to be backed up, the computer program product being embodied in a computer readable storage medium and comprising computer instructions for:

• allocating, upon receiving an instruction to execute the backing up, a storage area to store a snapshot produced at a time point designated by the instruction with respect to each time point designated by the instruction;
• checking, when original data is updated after the time point designated by the instruction, whether the original data corresponding to a place for which the updating has been executed at a time point immediately before the time point designated by the instruction is stored in the storage area allocated as a storage area to store the latest snapshot produced for the immediately previous time point;
• and
• storing, upon confirming that the original data is not stored, the original data immediately before the updating corresponding to the place for which the updating has been executed in only the storage area to store the latest snapshot.