[TriLUG] OT: Laptop Hard Drive

David Burton ncdave4life at gmail.com
Sat Nov 19 13:11:17 EST 2011


Wrong "ddrescue."   dd_rhelp works with Garloff's dd_rescue, rather than Diaz's
ddrescue <http://freecode.com/projects/addrescue> (a/k/a GNU ddrescue).

IMO, Diaz's ddrescue is superior.

Dave



On Sat, Nov 19, 2011 at 10:58 AM, Charles Mangin <option8 at option8.com>wrote:

> I've followed this thread off and on, so if this has already been
> mentioned, please forgive.
>
> For doing data rescue with ddrescue a helper script called DD_rhelp is
> super handy. It automates the process of skipping over damaged sections,
> then backing up to recover the good bits. It's my goto for data rescue on
> drives that aren't so damaged they need more hardcore techniques.
> --
> Charles Mangin
> option8 at option8.com
>
> David Burton <ncdave4life at gmail.com> wrote:
>
> >On Sat, Nov 19, 2011 at 8:25 AM, Joseph Mack NA3T <jmack at wm7d.net>
> >wrote:
> >
> >> On Fri, 18 Nov 2011, David Burton wrote:
> >>
> >>  ddrescue will never recover part of a sector.  SpinRite will do
> >that, but
> >>> ddrescue either recovers a sector or it doesn't, nothing in-between.
> >>>
> >>
> >> if sector 0,1 and 3 are OK, but sector 2 is not, what does ddrescue
> >do on
> >> the target piece of disk? write 0,1, then hop over 2 leaving whatever
> >junk
> >> was there and then write 3?
> >
> >
> >Yes.
> >
> >Note, however, that the ddrescue "log file" keeps track of which
> >sectors
> >have been recovered and which have not.  I.e., you can tell the
> >difference
> >between the recovered data and "whatever junk was there."
> >
> >In recent versions of ddrescue there is also a "--fill" option that can
> >be
> >used to write zeros to unrecovered sectors; see "fill mode" in the
> >documentation:
> >http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html
> >(A variant of the --fill option does the opposite: aim it at the bad
> >drive,
> >and it writes zeros everywhere except the bad sectors, so that you can
> >return the drive for warranty replacement and it will still test bad,
> >but
> >will not contain any of your data.)
> >
> >Also, some versions of Linux (including Parted Magic) apparently don't
> >let
> >ddrescue access individual sectors, even with the the -d option
> >specified.
> >On those versions of Linux, the granularity is usually 4kb (8 sectors),
> >so
> >if any of the 8 sectors in a cluster are unreadable the other 7 are
> >unrecovered, as well.
> >
> >Dave
> >--
> >This message was sent to: Charles Mangin <option8 at option8.com>
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