wiping deleted data - BCwipe multiple passes

[TigerUK]

I'm selling a used netbook by plcing it onto an auction site, and I've always taken precautions and used BCwipe to wipe free space before selling it on.

I've noticed that bcwipe has several types of wiping with fancy government and military names, which take 10+ hours to do on a regular laptop. I was wondering what the benefit of doing 7 passes on the disc was.

I always go for 1 pass, and if that doesn't work out, just cross my fingers that nobobody malicious is going to get their paws on my data.

I'm pretty sure 1 pass is absolutely fine, but my question is why do these professional instutitions prefer to do several passes? is there an actual possibility that a wipe will fail?

edit: sorry this really belongs in the Windows software section, posted here foolishly

 

[TigerUK]

thanks for the info.. I didn't actually use ccleaner, I just created a new admin account, logged onto there and deleted my previous account.

The gutmann wipe will take me 10 days to complete with 35 passes, and it just feels so OTT, I've taken the middle ground and went for a 10 hour wipe.

 

[TigerUK]

Brian, I've installed recuva to see what data I could recover after the BC wipe run using the first option US DoD 5220.22-M(ECE) took around 15 hours to wipe each 100GB partition.

I then had a look through the drive using Recuva, and all the user data were wiped clean. I have tonnes of entries on recuva like

filename -------- path
4xx ------------ C:\?\6XX\
4XX ------------ C:\?\

I'm guessing these files are filled with random 1's and 0's too making them impossible to recover.

Maybe the problem you were having with wiping was down to using Dban? maybe BCwipe would ueild better results, because I cannot see any trace of my previously deleted data. I used the thorough scan in Recuva as well, and not just a quick scan