[dsr_]

Secure erase depends on the technology of the drive and the prowess of your attacker.

If you fear the NSA seizing your disks, consider the tradeoffs of explosive disposal.

If you fear a technically-savvy reporter going through your trash bin, overwriting your disk three or four times with patterns will be fine. But it's probably faster to take a drill and make a couple of holes. Make sure you hit the platters.

If you are selling your old hardware and just don't want your unencrypted stuff to be recovered by a sixteen year old with no budget but lots of time, overwrite the disk once.

If you're trashing an SSD, make sure any patterns you use for overwriting are not compressed out of existence by the controller. Or pull off the controller and crunch it.

[rgbrenner]

The whole "overwrite xx times" is a myth. Overwriting it once with random data makes it completely unreadable. Overwriting it more than that is a complete waste of time.

http://computer-forensics.sans.org/blog/2009/01/15/overwriti...

http://www.howtogeek.com/115573/htg-explains-why-you-only-ha...

[sneak]

Anyone wiping disks in any of these ways in 2013 is doing it wrong.

Zeroize the keys. Then you don't need to worry about the disk.

If your data is something that would be a problem if the physical disks were stolen, don't store it on-disk unencrypted.