[CentOS] Question about dd (fill a hard disks' unused space with blanks)

On Jun 7, 2009, at 12:06 PM, Niki Kovacs wrote:

> Rainer Duffner a écrit :
>
>> Ideally, the zero'ing of the disk should take place before the OS is
>> installed, via a boot-cd and using dd with the disk-device itself
>
> Erm... how exactly would you go about that? Let's say I want to do  
> that
> with a Knoppix boot CD, and the only hard disk I have on the PC is
> /dev/hdc.

I've done the zeroing out thing on mounted filesystems before when I  
wanted to move the contents of a drive to another.  zeroing out before  
would be best if you planned to do an install, then back it up for  
later.  Otherwise, you end up with a lot of unused space that has  
remnants of old data scattered around.

It does take awhile.  Especially if you stuck the disk in an USB  
enclosure.