Q: Why is the “Deduplication Rate” in the history sometimes 0.0%?
A: The deduplication rate is calculated by comparing the number of hard links to the total number of files. If this is the very first backup to a new folder, there is no previous reference to link against, so the rate is 0%. It will increase with the second backup run as unchanged files are linked. It can also be 0% if DEDUP_ENABLE is turned off.