Asgrim

Well, I have finally decided to stop all this home serving malarkey. I just don’t have time to do it any more, and trying to maintain a comparable up time to other hosts is simply a nightmare. Not only that, it’s expensive on electric, and at the moment I still have no Internet (gah!), so it sort of rules out any hope for now.

Last night I spent some of the evening taking apart the server cabinet ready to sell on eBay. One thing I am particularly cautious about is data on the hard drives. Most people think that they need a whopping great magnet (like the ones that pick up cars in scrap yards), or that they need to drill holes in the drive and damage it irreparably. Well, thankfully, this is not the case.

All you need is DD. And, no I don’t mean my friend from Portsmouth, I mean the ancient UNIX command “dd” (sometimes nicknamed “disk destroy”). dd is a low-level data copier or converter. It works by writing blocks of data from one place to another. The very useful thing about UNIX/Linux is that it has these things called “devices”. One of these devices is called “/dev/zero”. It is a constant stream of 0. Lots of them.

Technically minded people might see where I’m going with this (well, they should already know what I’m talking about really…). Basically, an irrecoverable way of properly formatting a disk is top copy zeros all over the disk.

[root@oblivion /]# dd if=/dev/zero of=/dev/sda

The above command is all it takes to completely destroy a disk. If you are really paranoid, you could do it a few times, or intersperse it using /dev/random, like this:

dd if=/dev/zero of=/dev/sda
dd if=/dev/urandom of=/dev/sda
dd if=/dev/zero of=/dev/sda

According a data recovery company, there is less than zero percent chance of recovering data after using a single dd command. Some guys have even decided to make it a challenge.