Re: blu ray pseudo-overwrite

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Jan Gregor wrote:
> is it possible to correct the files via pseudo-overwrite

If the BD-R is already formatted for Pseudo-Overwrite and if you
can determine the block range of the damaged files, then this might
be possible.
The block range could be determined by

  path_to_file=...
  xorriso -indev /dev/sr0 -find "$path_to_file" -exec report_lba --


> or new session ?

This is possible if the medium is not closed sequential, and if
the filesystem is ISO 9660, and if the ISO formatter program
(mkisofs ?) allows you to overwrite existing file entries in the
directory tree of the ISO.
(xorrisofs would do it. I am not sure whether mkisofs or genisoimage
 bail out.)


> First method seems to me more natural, same is used when data written to
> formatted cannot be read and should be written to spare area.

Not completly. Pseudo-Overwrite uses unwritten blocks from the normal
data area and re-addresses them by a mechanism similar to the one
used for replacement blocks in the Spare Area.
It thus leaves orphaned block addresses which would need more remapping
if used.

growisofs will not use Pseudo-Overwrite to replace existing file
content. Maybe Linux and dd do.

Without knowing the output of dvd+rw-mediainfo and the filesystem type
i would rather bet on a ISO 9660 add-on session.


Have a nice day :)

Thomas