dvd+rw-format and growisofs

[jonas <jserrachinha@vianw.pt>]

Hi,

I'm using dvd-rw for my backups.
I'm doing this:
A script that run during the nigth and create 3 isos
dvd+rw-format -force=full -blank=full /dev/hdc (for each dvd)
growisofs -use-the-force-luke=DAO -dvd-compat -Z 
/dev/hdc=/downloads/dvdimage1.iso
growisofs -use-the-force-luke=DAO -dvd-compat -Z 
/dev/hdc=/downloads/dvdimage2.iso
growisofs -use-the-force-luke=DAO -dvd-compat -Z 
/dev/hdc=/downloads/dvdimage3.iso

The problem is i must make a full format before using again growisofs in 
the same dvd.
Is there another way to make my backups using the 3 isos and don't need 
to make a full format?

Thanks in advance
Joao