18.2 GB (20%). File defrag it's as slow as normal defrag :/ After 2 days, i still have 30% remaining.
Except 1 or 2 files, the biggest files i have are near 8GB, and not too many.
Anyway, i think my problem is not the time i need to defrag but the speed of my defrag. I read about defrag big disk in a few minutes, but a need a lot of hours :/
Edit: i found that my HD is "WD green", so it's "normal" to have low performance. But the HD's datasheet (http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-800026.pdf) says the average speed should be 175 MB/s.
With HD Speed (from steelbytes) i check it's true (at least, in the nearest areas of disk), but defraggler still says <2MB/s, and it's so slow.
I deleted a lot of files, and now i have ~45% disk free and 19% frag. After 4h (just with defraggler) i have 2k fragment less (9GB)