| 摘要 |
Data blocks lost at a primary mass storage 112 are restored while alowing the primary computer system 110 to access the lost data block before full restoration. Restoration accurs along two channels. In the first channel 104, read request issued by the primary computer system 110 are handled by obtaining the requested data block from the backup mass storage device 122. The retrieved data block is then written to the primary mass storage 110, thereby restoring the primary mass storage 110 for that data block. In the second channel of restoration 128, 138, a snapshot copy 126 of a selected data set 124 of the backup mass storage 122 is made and transported to the primary system 110. If the corresponding data block in the primary mass storage 112 has a current data block, the data block is not written from the snapshot copy 130 to the primary mass storage 112. Otherwise, the data block is copied from the snapshot copy 130 to the primary mass storage.
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