Disk-based images are more efficient for synthesizing. NetBackup processes the newest component images first in a synthesized backup, followed by sequentially older images. When two or more component images are written to the same tape, the tape movement can be inefficient compared to disk-based images.

Synthetic full backups are generated more quickly when built from disk-based incremental backups. If the synthetic full backup is also generated on disk, the run time is even faster. The disk copy then can be duplicated to tape.