摘要 |
A secondary subsystem reads first differential data recorded in a magnetic tape device into a magnetic disk device, and manages such data based on second differential data that was created based on the read first differential data and differential management information. Then, whether differential data exists in partial data is determined based on the differential management information, and, if such differential data exists, the partial data is read into a cache memory, and differential data is applied to the partial data. Meanwhile, if differential data does not exist, the partial data is read into the buffer. Moreover, new full data is recorded by writing the partial data, which was read into the cache memory or the buffer, onto the magnetic tape device in parallel with other read processing.
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