Why You Only Have to Wipe a Disk Once
Chris Hoffman (via Uli Kusterer):
To understand why the Gutmann method isn’t necessary for all drives, it’s important to note that the paper and method were designed in 1996, when older hard drive technology was in use. The 35-pass Gutmann method was designed to wipe data from any type of drive, no matter what type of drive it was – everything from current hard disk technology in 1996 to ancient hard disk technology.
As Gutmann himself explained in an epilogue written later, for a modern drive, one wipe (or maybe two, if you like – but certainly not 35) will do just fine[…]
I had not heard that before. However, these days most of my drives are encrypted with FileVault 2, so there’s probably little reason to wipe them, anyway.