On Sat, Jan 28, 2006 at 01:17:27PM +0100, Paul Bijnens wrote:
> 
> > Also dump can do incremential dumps.
> > Does it do them filewise or just from
> > the uninterpreted disk content?
> 
> Actualy that is up to the dump program itself,
> which I did not yet study in detail.
> But I believe it does it filewise, also because
> in most (all?) filesystem I know, there is
> no information that indicates which blocks of
> a file have changed.
> 
> But I can imagine that filesystems would implement
> that too, considering the immense size of the
> current disks and filesystems...
> 

I guess it could be done in the "soon to be released"
ZFS from Sun.  That file system maintains a 128bit
checksum on every block written for accuracy and error
correction on reads.

I could imagine a backup program using those data to
identify changed blocks and only saving modified blocks.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
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