What is the primary benefit of source-side deduplication compared to target-side deduplication?

Source-side deduplication is unrelated to isolating data for tape streaming - it is a network and storage efficiency mechanism with no direct relationship to tape tiering.

Increased storage capacity on the D2D device is the primary benefit of target-side deduplication, not source-side, because target-side stores the deduplicated data on the appliance itself.

Improved performance over low-bandwidth links is a secondary downstream effect; the primary and direct benefit is the reduction of data transferred between media servers and the D2D device, which answer D captures more precisely.

With source-side deduplication, duplicate data segments are identified and discarded on the backup media server before the data traverses the network to the disk-to-disk (D2D) appliance. This directly and measurably reduces network traffic between the media servers and the D2D device, which is the primary architectural advantage over target-side deduplication. Target-side dedup moves all raw, unprocessed data across the network first and only deduplicates upon arrival at the appliance.