A group of us are refurbishing donated disused lapops for disadvantaged school kids. In order to reassure donors, I need to quantify the risk of personal data surviving DBAN in spared tracks. I'm pretty sure it's going to be very small but I could do with some figures to justify that. Can anyone tell me the proportion of a typical hard drive's capacity that is hidden and reserved as spare tracks? I thought MHDD might tell me if I rummaged through its more obscur options but apparently not. I'm sure Steve would know if he stumbles across this.