CAUTION: Note that shred relies on a very important assumption:
that the file system overwrites data in place. This is the tra-
ditional way to do things, but many modern file system designs
do not satisfy this assumption. The following are examples of
file systems on which shred is not effective, or is not guaran-
teed to be effective in all file system modes: ...
Again, dd gets around this.
Actually it doesn't because you've no idea how the disk itself lays out
Maybe run the secure erase 25 times.
If the drive supports it a single secure erase should be fine. If not
then you need to pick an alternate disposal mechanism. The favourite
these days sometimes appears to be to pay someone to do it - so your
business can claim its discharged its liabilities and anyone in a
disaster should sue someone else ;)
Discs are smart enough to be considered as a small storage appliance
these days so are quite capable of re-arranging data internally as and
when it feels like it.