摘要 |
A data control system facilitates transfer of a virtual disk from a primary storage system to a secondary storage system. The data control system, responsive to an instruction to transfer the virtual disk, wherein the virtual disk comprises a plurality of data blocks, determines whether each of the plurality of data blocks is allocated or unallocated; for each data block of the plurality of data blocks determined to be allocated, the data control system reads the data block from memory in the primary storage system and transfers the data block for storage in the secondary storage system; and for each data block of the plurality of data blocks determined to be unallocated, the data control system refrains from reading the data block from memory in the primary storage system.
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