Inline deduplication is the removal of redundancies from data before or as it is being written to a backup device.
Inline deduplication reduces the amount of redundant data in an application and the capacity needed for the backup disk targets, in comparison to post-process deduplication. However, inline deduplication can slow down the overall data backup process because inline data deduplication devices are in the data path between the servers and the backup disk systems.
The main alternative to inline deduplication is post-processing deduplication. Post-processing deduplication products don't operate in the data path; rather, they deduplicate the backup data after it has been written to the backup disk system.