I have to delete some data from my harddisk permanently. Someone told me that data on harddisks can never really get deleted even one low-formats the disk. According to them, the most secure way to erase data is to crash the harddisk physically. Could anyone tell me why old data can still be retrieved after the whole disk are completely overwritten with 0? Does magnetic storage has a sort of "memory effect"? If it is true, ist there any other way of safely erasing data besides crashing harddisks?
And how about USB memory sticks? Are they also magnetic storage like harddisks? I guess they also have something like file allocation table on them. If I delete a file on memory sticks, does it permanently disapear? If I (low)format a memory stick, can data also be recovered as on a harddis?