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Re: dd - proper use or more suitable program

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  Re: dd - proper use or more suitable program Andy Smith <andy@strugglers.net> - 2016-11-11 18:00 +0100
    Re: dd - proper use or more suitable program Christian Seiler <christian@iwakd.de> - 2016-11-11 18:40 +0100
      Re: dd - proper use or more suitable program The Wanderer <wanderer@fastmail.fm> - 2016-11-11 19:20 +0100
        Re: dd - proper use or more suitable program Richard Owlett <rowlett@cloud85.net> - 2016-11-11 22:40 +0100
          Re: dd - proper use or more suitable program Andy Smith <andy@strugglers.net> - 2016-11-12 05:50 +0100
            Re: dd - proper use or more suitable program Richard Owlett <rowlett@cloud85.net> - 2016-11-12 09:20 +0100
    Re: dd - proper use or more suitable program Nicolas George <george@nsup.org> - 2016-11-11 19:00 +0100
      Re: dd - proper use or more suitable program Richard Owlett <rowlett@cloud85.net> - 2016-11-11 22:40 +0100
        Re: dd - proper use or more suitable program Christian Seiler <christian@iwakd.de> - 2016-11-12 08:40 +0100
          Re: dd - proper use or more suitable program Richard Owlett <rowlett@cloud85.net> - 2016-11-12 09:30 +0100
            Re: dd - proper use or more suitable program Richard Owlett <rowlett@cloud85.net> - 2016-11-12 18:30 +0100
              Re: dd - proper use or more suitable program Pascal Hambourg <pascal@plouf.fr.eu.org> - 2016-11-12 19:30 +0100
                Re: dd - proper use or more suitable program Richard Owlett <rowlett@cloud85.net> - 2016-11-12 20:30 +0100
                  Re: dd - proper use or more suitable program Ben Caradoc-Davies <ben@transient.nz> - 2016-11-12 21:00 +0100
                    Re: dd - proper use or more suitable program Brian <ad44@cityscape.co.uk> - 2016-11-12 21:10 +0100
                  Re: dd - proper use or more suitable program <tomas@tuxteam.de> - 2016-11-12 22:00 +0100
                    Invoking ddrescue Richard Owlett <rowlett@cloud85.net> - 2016-11-13 04:10 +0100
                      Re: Invoking ddrescue "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-13 13:00 +0100
                        Re: Invoking ddrescue <tomas@tuxteam.de> - 2016-11-13 13:10 +0100
                      Re: Invoking ddrescue <tomas@tuxteam.de> - 2016-11-13 13:00 +0100
                      Re: Invoking ddrescue "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-13 13:40 +0100
                        Re: Invoking ddrescue Pascal Hambourg <pascal@plouf.fr.eu.org> - 2016-11-13 13:50 +0100
                          Re: Invoking ddrescue Nicolas George <george@nsup.org> - 2016-11-13 14:00 +0100
                          Re: Invoking ddrescue "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-13 14:40 +0100
                            Re: Invoking ddrescue Pascal Hambourg <pascal@plouf.fr.eu.org> - 2016-11-13 15:10 +0100
                              Re: Invoking ddrescue "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-13 16:10 +0100
                                Re: Invoking ddrescue Richard Owlett <rowlett@cloud85.net> - 2016-11-13 17:30 +0100
                      Re: Invoking ddrescue Brian <ad44@cityscape.co.uk> - 2016-11-13 15:20 +0100
                      Progress report Re: Invoking ddrescue Richard Owlett <rowlett@cloud85.net> - 2016-11-14 20:20 +0100
                        Re: Progress report Re: Invoking ddrescue Jonathan Dowland <jmtd@debian.org> - 2016-11-14 21:20 +0100
                          Re: Progress report Re: Invoking ddrescue Richard Owlett <rowlett@cloud85.net> - 2016-11-14 22:00 +0100
                        Re: Progress report Re: Invoking ddrescue <tomas@tuxteam.de> - 2016-11-14 21:30 +0100
                          Re: Progress report Re: Invoking ddrescue Richard Owlett <rowlett@cloud85.net> - 2016-11-14 22:20 +0100
                        Re: Progress report Re: Invoking ddrescue "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-14 21:30 +0100
                          Re: Progress report Re: Invoking ddrescue Richard Owlett <rowlett@cloud85.net> - 2016-11-14 22:10 +0100
                          Re: Progress report Re: Invoking ddrescue Pascal Hambourg <pascal@plouf.fr.eu.org> - 2016-11-17 20:20 +0100
                        SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Richard Owlett <rowlett@cloud85.net> - 2016-11-14 23:40 +0100
                          Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Brian <ad44@cityscape.co.uk> - 2016-11-15 00:30 +0100
                            Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Richard Owlett <rowlett@cloud85.net> - 2016-11-15 04:00 +0100
                              Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Brian <ad44@cityscape.co.uk> - 2016-11-15 21:00 +0100
                                Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] <tomas@tuxteam.de> - 2016-11-15 22:00 +0100
                          Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-15 12:50 +0100
                            Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Brian <ad44@cityscape.co.uk> - 2016-11-15 13:30 +0100
                              Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-15 13:50 +0100
                            Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Richard Owlett <rowlett@cloud85.net> - 2016-11-15 13:50 +0100
                            Re: SUC[C]ESS!!! - was [Re: Progress report Re: Invoking ddrescue] David Wright <deblis@lionunicorn.co.uk> - 2016-11-15 16:30 +0100
                              Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] "Thomas Schmitt" <scdbackup@gmx.net> - 2016-11-15 17:20 +0100
                                Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue] Greg Wooledge <wooledg@eeg.ccf.org> - 2016-11-15 17:30 +0100

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#174777 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

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Hash: SHA1

On Tue, Nov 15, 2016 at 07:57:11PM +0000, Brian wrote:
> On Mon 14 Nov 2016 at 20:49:48 -0600, Richard Owlett wrote:

[...]

> > writen by some one who actually read my reply to tomas?????????????????????
> 
> Reading and understanding. From this thread you will appreciate the
> difference,

As someone somehow involved in this discussion, I don't know whether
I'm thoroughly happy with the ensuing "conflict". I offered some
advice the interpretation of I leave to you all. Many interpretations
fit. Thus a plea: let it rest. If it helped, it did its job :-)

regards
- -- t
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=JIuo
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#174740 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

Hi,

Richard Owlett wrote:
> ddrescue has run to completion without _reported_ errors for all partitions
> of the drive. I understand that does *NOT* guarantee that the files are not
> corrupt.

A coarse test would be to mount the partitions and to let some archiver
crawl the tree to read the content of each data file.

Create a mount point for the partition to be tested:

  mkdir /mnt/partition

Then with each of the copied partition files /mnt/my_sdb6/my_sdc* do:

  mount -o loop,ro,nodev,noexec,nosuid /mnt/my_sdb6/my_sdc1 /mnt/partition

  tar cf - /mnt/partition | wc -c

  umount /mnt/partition

If tar does not report i/o errors and wc tells a plausible byte count,
then all might be well.

mounting has to be done as superuser, of course.
man 8 mount paragraph "Mount options for ntfs" says that you will have
to do the tar part as superuser, unless you assign it at mount time
to a less powerful user id. I read from the manual something like:
  -o loop,ro,nodev,noexec,nosuid,uid=NORMAL_USER_ID,umask=400
but have no ntfs to test whether this makes all file readable for the
desktop user of whom you obtained the number NORMAL_USER_ID by:
  echo $UID


Does somebody know an entertaining filter in Debian, which one could put
between tar and wc to see a progress counter ?


Not so easy to test:
- The file content may still be damaged on application level (e.g. zeros
  where other data should be).
- Important parts of the tree may be missing.


Have a nice day :)

Thomas

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#174741 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

On Tue 15 Nov 2016 at 12:39:49 +0100, Thomas Schmitt wrote:

[...]

>   tar cf - /mnt/partition | wc -c

[...]

> Does somebody know an entertaining filter in Debian, which one could put
> between tar and wc to see a progress counter ?

apt-get install pv.

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#174743 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

Hi,

i wrote:
> > Does somebody know an entertaining filter in Debian, which one could put
> > between tar and wc to see a progress counter ?

Brian wrote:
> apt-get install pv.

Oh yes. Waiting is much more fun with

  tar cf - /mnt/partition | pv | wc -c


Have a nice day :)

Thomas

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#174742 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

Your timing was good. I woke up this morning asking myself, "How 
do I read the recovered data?" ;/
However, Murphy's Law rules. Something died in my laptop 
dedicated to this experiment and systemd complains about the 
drive. There other strange symptoms so I decided to reinstall 
Debian [yes brute force approach but no data on that hardware]. 
The drive with the recovered data is readable on another machine. 
Now to troubleshoot the failed laptop.
[snip instructions for reading recovered data]

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#174754 — Re: SUC[C]ESS!!! - was [Re: Progress report Re: Invoking ddrescue]

On Tue 15 Nov 2016 at 12:39:49 (+0100), Thomas Schmitt wrote:
> Richard Owlett wrote:
> > ddrescue has run to completion without _reported_ errors for all partitions
> > of the drive. I understand that does *NOT* guarantee that the files are not
> > corrupt.
> 
> A coarse test would be to mount the partitions and to let some archiver
> crawl the tree to read the content of each data file.
> 
> Create a mount point for the partition to be tested:
> 
>   mkdir /mnt/partition
> 
> Then with each of the copied partition files /mnt/my_sdb6/my_sdc* do:
> 
>   mount -o loop,ro,nodev,noexec,nosuid /mnt/my_sdb6/my_sdc1 /mnt/partition
> 
>   tar cf - /mnt/partition | wc -c
> 
>   umount /mnt/partition
> 
> If tar does not report i/o errors and wc tells a plausible byte count,
> then all might be well.
> 
> mounting has to be done as superuser, of course.
> man 8 mount paragraph "Mount options for ntfs" says that you will have
> to do the tar part as superuser, unless you assign it at mount time
> to a less powerful user id. I read from the manual something like:
>   -o loop,ro,nodev,noexec,nosuid,uid=NORMAL_USER_ID,umask=400
> but have no ntfs to test whether this makes all file readable for the
> desktop user of whom you obtained the number NORMAL_USER_ID by:
>   echo $UID

That umask looks odd. It should be set to the bits whose permission
you want to withhold. umask=022 would be a sensible choice as it
allows you to remount rw later, but still protect all files from
being written to except by the owner. (Yes, yes, I know, noone else
uses this machine...)

> Not so easy to test:
> - The file content may still be damaged on application level (e.g. zeros
>   where other data should be).
> - Important parts of the tree may be missing.

Aren't we getting carried away a bit? We have a "defective" drive
(also described as "flaky") that has been copied satisfactorily, is
reportedly "unreliable" and in "bad shape", and has "unidentified
problems" on the first partition which was running windows.
IIRC the only problem reported was that XP refused to boot.
The OP has signed his disclaimer (above) so there's no need to
be pessimistic about the data at this stage, is there.

Cheers,
David.

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#174759 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

Hi,

David Wright wrote:
> That umask looks odd. 

Using a thing named "umask" to "Set the file permission on the filesystem"
is odd. No further speculation but only experiments would give clarity.


i wrote:
> > Not so easy to test:

> Aren't we getting carried away a bit?

After suspicion arised over data integrity, nothing that is important
can be considered ok before it has been tested.

All that is known yet is that the disk doesn't boot MS-Windows any more
and that attached to the GNU/Linux machine no bad blocks were reported
by ddrescue.
Between both facts, any kind of filesystem corruption or file content
corruption is still possible.


Have a nice day :)

Thomas

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#174761 — Re: SUCESS!!! - was [Re: Progress report Re: Invoking ddrescue]

On Tue, Nov 15, 2016 at 05:18:25PM +0100, Thomas Schmitt wrote:
> David Wright wrote:
> > That umask looks odd. 
> 
> Using a thing named "umask" to "Set the file permission on the filesystem"
> is odd. No further speculation but only experiments would give clarity.

It's how fat/vfat mounts work in Linux.  The file system has no internal
owners, groups or permissions, so the kernel simply assigns them.
By default, all files on a vfat mount show up as root:root 666 and
all directories as root:root 777 as modified by the umask of the
mounting process.  So if you've got a umask of 022 when you mount, then
it's 644 and 755 respectively.  Explicitly specifying a umask in the
fat/vfat mount options overrides that.  See mount(8) for details.

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