QUESTION :
I have tried Eraser, sdelete, Shred agent & others-none has successfully wiped the free space on my
hard drive.
Using Easeus Data Recovery, I am able to recover over 400,000 files-all intact (including ebooks, and gif, tif and icon files).
What am I doing wrong?
ANSWER :
If you’re only doing a single pass, the data would still be “easily” recoverable. Most corporate/government/military agencies require multiple passes of alternating bits to wipe data out “completely”… But even that isn’t 100%.
When I worked for a large corporate bank, we were required to use a military-grade wiping software and run at least 15 passes, with the passes alternating between writing all 0’s on one pass, then all 1’s on the next, for each drive we had to wipe.
Here are some references for you:
http://en.wikipedia.org/wiki/Data_erasure
http://en.wikipedia.org/wiki/Data_remanence (This is the one that will answer your question)
To paraphrase:
“Data remanence is the residual representation of data that remains even after attempts have been made to remove or erase the data. This residue may result from data being left intact by a nominal file deletion operation, by reformatting of storage media that does not remove data previously written to the media, or through physical properties of the storage medium that allow previously written data to be recovered.”