| 摘要 |
Source data is more efficiently copied to log structured target storage by pre-configuring the target storage. The invention may be practiced in a system including a host, a storage controller, and the target storage. The host maintains a directory identifying logical units of stored data, and the storage controller maintains records classifying storage space as uncollected free space, collected free space, or space-in-use. First, the host receives input including source data and specification of a logical unit for the source data. In response, the host directs the storage controller to classify any storage space of the log target storage containing data of the specified logical unit as uncollected free space. This pre-configures the log structured storage to more efficiently receive the source data. In another embodiment, the host may consult the directory to determine whether the specified logical unit already exists, and only if so, proceed to direct re-classification of the storage space as uncollected free space. In another embodiment, the host may blindly issue a "space release" instruction for the specified logical unit, which is ignored by the storage controller if the logical unit does not already exists in storage. After pre-configuration, the host instructs the storage controller to write the source data to the log structured storage. The storage controller performs the write, and also changes the directory to classify the storage space now occupied by source data as space-in-use.
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