Hey. I have a Samsung 850 EVO 250GB SSD on Windows 8 and I haven't checked how full it was for a while. I just had a random BSOD and when I started up Steam told me it didn't have enough SPAAACE to update (I have Steam on my SSD but not my games). I was curious and went and saw that my SSD was 99% full. I wondered what could've caused it so I checked with WinDirStat and it said that it only had 70GB of data on it. Right clicking and checking the storage that each of the base folders didn't add up too.
WinDirStat
This PC
I just right clicked on C: and went to Tools > Error checking and it said that it found an error that needs to be repaired.
WinDirStat
This PC
I just right clicked on C: and went to Tools > Error checking and it said that it found an error that needs to be repaired.