On Sun, 12 Jun 2005, Rodrigo Barbosa wrote:
> On Sun, Jun 12, 2005 at 03:45:19AM +0200, Dag Wieers wrote:
> > > Check my other post regarding this. Dump won't clone wholedisks. It
> > > will clone filesystems (with all metadata intact).
> >
> > The problem with a broken disk is that your filesystem may not be correct.
> > And you can't do a fsck to correct the inconsistencies because the disk is
> > not reliable.
> >
> > That's why you require something like ddrescue, so you can copy everything
> > that is still accessible and fill the blank spaces in with zero-blocks.
> > So it doesn't abort or truncate the output like dd, maybe dd conv=noerror
> > is similar but ddrescue has other features like proper status info during
> > copying and decreasing blocksize when blocks fail to be read.
>
> I never tried ddrescue, so I can't comment.
>
> But, as far as I remember, dump will only abort if you get an error
> on the writing side. Memory can be at fault here, tho.
But dump expects that your filesystem can be trusted, that it is still
consistent. Which, if you have a broken disk, is not (necessarily) the
case.
I'm not talking about a backup mechanism, I'm sure dump has its use. But
when you have a failing drive (which was the topic) you better not use
something that expects a working filesystem and you most certainly want to
recover your filesystem on the broken disk (fsck).
BTW An example of a broken filesystem could be that directories appear to
be missing or filled with garbage. Recursively scanning through the
filesystem could yield unexpected results.
-- dag wieers, dag@xxxxxxxxxx, http://dag.wieers.com/ --
[all I want is a warm bed and a kind word and unlimited power]
