Re: [Bug-ddrescue] Suggestion / feature request - bad head mapping

[Robert Trevellyan]

partclone will generate a domain mapfile for use with ddrescue using the
--domain option. Like any tool that does this, it will only succeed if the
block bitmap is intact and readable.

Robert Trevellyan


On Tue, Jan 9, 2018 at 5:21 AM, Peter Clifton <address@hidden> wrote:

> >
> >         > >
> > >     >
>
> >
> >         > > Domain mapfiles can be used for both purposes. You need a
> separate tool to generate mapfiles containing the sectors accessible
> through each head. Then, get the sector map of the desired files using
> another utility (in mapfile format), and finally combine the mapfiles using
> the ddrescuelog command.
> > >
> > >     >
> >     It would be probably best to automate this using some wrapper (with
> a GUI or curses-based interface). It's definitely beyond the scope of
> ddrescue itself.
> >
>
> Thanks for the reply. As the recovery progressed it became apparent that
> the LBA to physical mapping is quite complex. I suspect the proprietary
> recovery tools use manufacturer specific (and undocumented) ata commands /
> serial port debug to extract this information from the drive).
>
> Do you happen to know of any recipes to extract filesystem block usage in
> mapfile format? I couldn't find anything existing, but don't want to
> re-invent a new utility.
>
> My thinking so far...
>
> ntfsclone allows a meta-data only clone of an NTFS volume into a sparse
> file. Assuming it can read the meta-data blocks, this sparse file should
> match the layout of the metadata blocks - although I'm not certain whether
> this includes any indirect blocks (zfs terminology?) or bitmaps locating
> all the user file data. (I'm no expert on the NTFS layout).
>
> The next step might be to write a utility which implements a data-source
> for ntfsclone which overlays the sparse image of metadata (so the clone
> utility "sees" the filesystem), whilst constructing an extent map of all
> reads made whilst making a full clone. This extent map could then be used
> to feed ddrescue.
>
> Peter
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