> I have seen where people use dd to do this sort of thing to. I read > somewhere that if you do a dd and put in all 1's, then all 0's then back > again that it is very hard to get any data back off the drive. I think > if you do it like over a dozen times, it is deemed impossible to get > anything back. I think that is the Government standard of it's gone.
I've heard the old attacks to recover data from a zerod drive are no longer viable for disks of greater capacity than about 10G. I haven't seen the information myself, however. A single pass using dd would probably a good way of detecting any existing bad blocks, so a smartctl then dd then smartctl again and a diff of the results may be interesting. I just use a 1TB software mirror for my backups.
