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

Sun Jun 7 16:22:20 UTC 2009
Niki Kovacs <contact at kikinovak.net>

Hi,

I'm currently experimenting with G4U (Ghost for Unix), a small cloning 
application sending disk images to an FTP server.

The application reads the whole disk bit by bit, compresses it and then 
stores it remotely. Due to this approach, it's more or less 
filesystem-independent. The drawback is that it sometimes results in 
huge image files.

Now I'm currently following a hint which suggests to fill the disks' 
unused space with zero bits. Here's the command for that:

# dd if=/dev/zero of=/0bits bs=20M
# rm /0bits

Now I gave that a shot, but after half an hour or so, I got a bit 
impatient. Now the computer does not respond any more. Does that mean 
he's just way too busy with dd? Or is there some mistake in the command? 
As I see it, it will just be chugging on and on, no? Shouldn't there be 
a 'count=x' option somewhere?

Niki