Osiris
3rd October 2008, 12:09
When i tried to backup my video DVDs as ISO images
to HDD i could see the common problem, that some
combinations of discs and drives do no work without
errors.
So to be able to do the backups with every drive i want,
i simply slow down the drive and use ddrescue to copy
only one block at a time (only tested with Linux, should also work with cygwin):
hdparm -X 34 -c 0 -u 0 -E 1 /dev/hdc
hdparm -X00 /dev/hdc
setcd -x 1 /dev/hdc
rm logfile
ddrescue -b2048 -c1 -R -d --max-size=11222333444 /dev/hdc video.iso logfile
With this reading, ddrecue and the linux kernel do report no
error and the image is intact; the image can be mounted,
mplayer and VLC player can play the DVD and via sha512sum i
see that different drives do read the same data!
So the DVDs are simply badly produced so that the error correction of
some DVD drives are too slow, because after slowing down i can see no
error with an old LG HL-DT-ST DVDRAM GSA-4160B, an very old NEC
DVD_RW ND-1300A and a TSSTcorpCD/DVDW TS-L632D.
Therefore on Video DVDs there are no real errors; it' only fake!
The reading with single speed (1,32 MB/s) is a little slow, but it's
sufficient for a backup.
It works e. g. with the DL-DVDs Catwoman from WB
and Dinotopia from BMG.
If you still get errors, you can try slowing down via the BIOS settings,
switching off DMA
hdparm -d 0
as the (additional) third line of commands and you can
try ddrescue with the option -r1 or -n instead -R and
maybe using ddrescue without -d helps.
Another option is updating the firmware. :)
to HDD i could see the common problem, that some
combinations of discs and drives do no work without
errors.
So to be able to do the backups with every drive i want,
i simply slow down the drive and use ddrescue to copy
only one block at a time (only tested with Linux, should also work with cygwin):
hdparm -X 34 -c 0 -u 0 -E 1 /dev/hdc
hdparm -X00 /dev/hdc
setcd -x 1 /dev/hdc
rm logfile
ddrescue -b2048 -c1 -R -d --max-size=11222333444 /dev/hdc video.iso logfile
With this reading, ddrecue and the linux kernel do report no
error and the image is intact; the image can be mounted,
mplayer and VLC player can play the DVD and via sha512sum i
see that different drives do read the same data!
So the DVDs are simply badly produced so that the error correction of
some DVD drives are too slow, because after slowing down i can see no
error with an old LG HL-DT-ST DVDRAM GSA-4160B, an very old NEC
DVD_RW ND-1300A and a TSSTcorpCD/DVDW TS-L632D.
Therefore on Video DVDs there are no real errors; it' only fake!
The reading with single speed (1,32 MB/s) is a little slow, but it's
sufficient for a backup.
It works e. g. with the DL-DVDs Catwoman from WB
and Dinotopia from BMG.
If you still get errors, you can try slowing down via the BIOS settings,
switching off DMA
hdparm -d 0
as the (additional) third line of commands and you can
try ddrescue with the option -r1 or -n instead -R and
maybe using ddrescue without -d helps.
Another option is updating the firmware. :)