5TB is 2 weeks old nothing wrong with it.
I just downloaded the latest Defraggler from the builds page (no install, zip) 2.18.945 x64, latest as far as I can tell.
I've been using other defrag tools previously in the last week, and decided to try Defraggler again.
The drive is used primarily for raw OBS encodes only ( large 2GB+ video encodes).
Edit: OS is Windows 8.1 64 Pro