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Recovery from optical media that ignores read errors

I have backups of files archived on optical media (CDs and DVDs). All of them have par2 recovery files stored on separate media. Even in cases where there are no par2 files, minor read errors on one optical disc can be read well on another disc.

The fact is that when reading faulty media, the reading time is very, very long, because devices tend to repeat several times.

The question arises: how can I control the number of attempts (i.e. do not set any attempts or only one attempt)? Some kind of system call? A library that I can download? Should I work with SCSI level?

The question is mostly about Linux, but any Win32 pointers will be more than welcome.

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7 answers

man readomThe program that comes with cdrecord:

   -noerror
          Do not abort if the high level error checking in readom found an
          uncorrectable error in the data stream.

   -nocorr
          Switch  the  drive  into  a mode where it ignores read errors in
          data sectors that are a result of uncorrectable  ECC/EDC  errors
          before reading.  If readom completes, the error recovery mode of
          the drive is switched back to the remembered old mode.
   ...

   retries=#
          Set the retry count for high level retries in readom to #.   The
          default  is  to do 128 retries which may be too much if you like
          to read a CD with many unreadable sectors.
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The best tool available is dd_rhelp. Simply

dd_rhelp /dev/cdrecorder /home/myself/DVD.img

take a cup of tea and see beautiful graphics.

Details of the dd_rhelp rpm package:

dd_rhelp ddrescue , badsectors. dd_rhelp , dd_rescue. , dd_rhelp . dd_rescue.

Ctrl-C, , , dd_rhelp , , dd_rescue. , ASCII , .

, .

DAG Red Hat, .

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, hdparm ( ), , CD-ROM , . , , CD-ROM .

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dd , , sg_dd, (1) (1m), (2) (3).

linux - sdparm. :

sudo sdparm --set=RRC=0 /dev/sr0

/dev/sr0 - .

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, SCSI , , ASPI-API. VSO ( / ) API, Patin-Couffin, :

http://en.wikipedia.org/wiki/Patin-Couffin

. SCSI, USB, SATA, ATA, IDE . , ATAPI, SCSI -.

, linux , .

:

Blindread/blindwrite cd-rom, , -.

, . , CD-ROM , , , (?) CD-ROM.

ISO, , ISO .

-Adam

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dd (1) - .

dd if =/dev/cdrom of = image bs = 2352 conv = noerror, notrunc

The drive may still try again a little, but I don’t think you are improving without changing the firmware.

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Look at the ASPI interface. Available for both Windows and Linux.

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