Steve Lord wrote:
>
> On Tue, 2001-11-13 at 10:10, Yannick Ribau wrote:
> > hi all,
> >
> > is it possible to make a "dd conv=noerror /dev/hda2 /dev/hda3" to have a
> > complete backup of my root filesystem, then do a
> > "dd conv=noerror /dev/hda3 /dev/hda2" to restore it, in case of a soft
> > filesystem problem ?
> >
> > (both partitions have the exact same size)
>
> On a live filesystem this is not too smart an idea, the block cache and
> the live filesystem are not totally coherent - in fact depending on the
> kernel version they can be totally incoherent (changes to one are
> invisible in the other).
Out of curiosity, is there any reasonable way to access both block cache
and the filesystem, such that the combined information is an
"atomically" correct state at all times? I'm wondering what would be
required to create a merging version of dd to do the recombining, or
else to be able to at least write the cache out in a way that makes
later retrieval practical (where recombining could be done by a separate
program even if dd stores cache and live disk separately).
D. Stimits, stimits@xxxxxxxxxx
>
> You at least need to do a remount readonly to make the disk
> image stable - and this will fail if a file is open for writing
>
> Steve
>
> >
> > Yannick.
> >
> --
>
> Steve Lord voice: +1-651-683-3511
> Principal Engineer, Filesystem Software email: lord@xxxxxxx
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