On Tuesday 04 September 2001 14:31, you wrote:
> Tom Oehser wrote:
> > > > idea in backing up all the empty space.
> > >
> > > How about compression? Isn't the empty space zeroed?
> >
> > No. It is full of detritus. Deleting a file just flips a bit in the
> > directory. You have to make a big file of zeros that fills it if you
> > want to dd a partition efficiently.
>
> Hmm. That might not be that bad of a thing to have to do. Mount
> the partition at /mnt/C then do cat /dev/null> /mnt/C/ZEROES.000
> until it fills up, then unmount it, then do the dd into gzip into backup
> media.
I take your correction about /dev/null being /dev/zero. I was just thinking
"What does he know that I don't?" I always saw /dev/null as the linux
equivelant of the Write Ony Memory, whose datasheet I still have
That aside, why bother what is on the disk? In a FAT system, the disk gets
filled from end to end, bits get wiped in the middle by a user deleting, and
then it gets filled again. If you dd, you get the entire disk, whether it's
full or not; if you use cp or tar, you just get the files.
--
Regards,
Declan Moriarty
Applied Researches - Ireland's Foremost Electronic Hardware Genius
A Slightly Serious(TM) Company
Success covers a multitude of blunders - G.B. Shaw.
