I hve a defective HDD that was under warranty and was replaced. Now I need to return the old HDD - the manufaturer requests it . I belive that my data on the old HDD may still be accessible and before I return it, I want to make the data on the HDD completely inaccessible. How can I do this? Thanks!
I doubt there is any way to make it "completely inaccessible" and still fulfill your obligations (e.g. returning a melted drive probably wouldn't fly). Is the drive still accessible at all (e.g. does the computer recognize it when you attach it)? If so there is software that can write every sector several times with different bit patterns which is pretty damn good at making sure your data can't be recovered (NSA probably still could), otherwise you need to look at hardware solutions (ex: bulk magnetic eraser)
I had a similar situation with a Maxtor. Started making grinding noises and was inaccessible. It was replaced and I had to send the old one back. I took to a local store that repairs computers and happened find one with a bulk eraser (he described it as a big magnet). I gave it to him, he ran it through and it was done. I then put it in the box that the replacement came in and sent it back. I'm really not sure what is involved with erasing a hard drive, but it wouldn't bother me if the data was still partially on there. You might call around and ask to see if someone can erase it without accessing it locally. Otherwise, send them the replacement drive back that you got and get a new one online. They are cheap. You have 30 days usually to send the replacement drive back.