Re: Re: unable to read some of a DVD contents

[scdbackup@gmx.net]

Hi,

> what is the indicator that the burn process was only 95% completed?

The only reliable indicator seems to be checkreading
by all drives which shall be able to read the DVD.

This would mean either

- to compare each file on the DVD with its original
  on hard disk (if the files on disk did not change
  meanwhile)

- or to compare the data image on DVD with the data
  image on disk (if the image was stored on disk)

- or to compare the data image on DVD with a checksum
  which was made when that image was written to DVD.
  (I prefer this method.)


I just had to trash a previously used DVD-RW which
failed to pass the checksum test with errors at the
very start of the image. After a test re-write it
failed to deliver the last 2 MB (but the start of the
test image was ok). A third re-write yielded missing
300 MB at the end of the media.
The fourth try failed with 
   :-[ PERFORM OPC failed with SK=3h/ASC=73h/ACQ=03h]: Input/output error
According to  keys.txt  : 
   3  73  03       POWER CALIBRATION AREA ERROR
(Not much idea what that means but it looks ugly and fatal) 

I successfully tested another DVD-RW from the same
spindle as the ill one. So the burner is not to blame.

It is not about the manufacturer of the media, not even
about the particular lot. It is not about the number of
re-uses. The sucessfull DVD-RW is in heavy test use, has
a nice collection of scratches ... and it works fine.
The ill one had its third or fourth re-use, looks shiny
and smooth ...

A theory which emphasizes the influence of moon phases or
geomantic radiation would probably be as successful as
the usual methods of DVD compatibilty prediction.


Have a nice day :)

Thomas