Brendan Jones

Q: Can I bit copy an optical disk that won't mount?

I have a Mac Pro 1,1 with 2 optical drives in it.  I have an 8 year old DVD-R (a playable DVD-video) which won't mount in either optical drive - Mac says it is in a format it can't recognise.  Putting it in a DVD player simply says "Can't play disk".

 

Is there any way I can bit-copy it to try various recovery tools to extract the content?  Hopefully it's just the disk header that's corrupted, if I can bit copy it there is a good chance I can recover the contents as it was all linearly written in one go.

 

Thanks.

Mac Pro, Mac OS X (10.6.8), 2 x 2.66 Dual Core

Posted on May 28, 2016 6:37 PM

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Q: Can I bit copy an optical disk that won't mount?

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  • Helpful answers

  • by bigschwabbel,Helpful

    bigschwabbel bigschwabbel May 29, 2016 3:55 AM in response to Brendan Jones
    Level 3 (808 points)
    May 29, 2016 3:55 AM in response to Brendan Jones

    1. insert a working disc in one of your drives

    2. open Terminal and type "mount", hit the ENTER key

    3. find the disc in the list of mounted volumes and remember/write down the drive name, i.g. /dev/disk4s0

    4. replace the working disc with the broken one

    5. type "dd bs=2048 if=/dev/disk4s0 of=./Desktop/image.iso" and hit the ENTER key

        Replace "disk4s0" with the correct drive number.

        If you get a "permission denied" try "sudo dd bs=...". Enter your user password when asked.

  • by Brendan Jones,

    Brendan Jones Brendan Jones May 29, 2016 4:00 AM in response to bigschwabbel
    Level 2 (208 points)
    Desktops
    May 29, 2016 4:00 AM in response to bigschwabbel

    Thanks for the tip... but unfortunately it didn't work.  If I put the non-working disk in my upper superdrive, the disk spins up and eventually Finder gives the message "The disk you inserted is not readable on this computer".  I click "ignore" rather than "eject" then tried:

     

    % dd bs=1024 if=/dev/disk4 of=./Desktop/image

    dd: /dev/disk4: Input/output error

    0+0 records in

    0+0 records out

    0 bytes transferred in 0.002291 secs (0 bytes/sec)

     

    If I try the lower superdrive, the disk doesn't even seem to spin up and Finder says nothing.  Trying dd yields:

     

    % dd bs=1024 if=/dev/disk6 of=./Desktop/image

    dd: /dev/disk6: Device not configured

    0+0 records in

    0+0 records out

    0 bytes transferred in 0.000095 secs (0 bytes/sec)

     

    Is the disk beyond redemption?

  • by bigschwabbel,

    bigschwabbel bigschwabbel May 29, 2016 7:23 AM in response to Brendan Jones
    Level 3 (808 points)
    May 29, 2016 7:23 AM in response to Brendan Jones

    You could try it with a working disc, just to make sure your drives are OK and that you didn't make any mistakes in Terminal.

     

    Check the broken disc for scratches and fingerprints.

     

    Optical media have a limited lifespan, mostly depending on how you store them (exposure to changing temperatures, humidity, UV light). After 8 years chances are high, that the data went bad.

  • by Brendan Jones,

    Brendan Jones Brendan Jones May 31, 2016 5:45 AM in response to bigschwabbel
    Level 2 (208 points)
    Desktops
    May 31, 2016 5:45 AM in response to bigschwabbel

    The disk is clean and was kept in a DVD case with cover in a glass fronted cabinet.  Maybe this particular batch of DVD-R (Imation) was dodgy because others of similar vintage also fail to mount.  I have other optical disks from similar era or older that are fine.

     

    With a working DVD the dd command produces the response:

     

    % dd bs=1024 if=/dev/disk4 of=./Desktop/image.dmg

    dd: /dev/disk4: Resource busy

     

    The disk is just sitting in the tray.  No app is using it (such as DVD Player).  DVD Player happily plays it if called up.

  • by lllaass,

    lllaass lllaass May 31, 2016 7:22 AM in response to Brendan Jones
    Level 10 (187,749 points)
    Desktops
    May 31, 2016 7:22 AM in response to Brendan Jones

    Try reading/copying them in another DVD drive. That sometimes works

  • by Brendan Jones,

    Brendan Jones Brendan Jones Jun 1, 2016 4:50 AM in response to lllaass
    Level 2 (208 points)
    Desktops
    Jun 1, 2016 4:50 AM in response to lllaass

    I tried both Mac Pro optical drives, my DVD player, and a drive in my PC at work.  No dice.  I think this disk is dead

     

    Thanks to everyone though for your helpful suggestions.

  • by Christian Stueben,

    Christian Stueben Christian Stueben Jun 1, 2016 8:22 AM in response to Brendan Jones
    Level 1 (120 points)
    Mac OS X
    Jun 1, 2016 8:22 AM in response to Brendan Jones

    i dont know what Toast CD for Mac or other CD copy / burning software can do, but Nero (Windows) can copy CDs with "ignore error option". if this might help, will strongly depends on the missing data. Missing Directory information always is much worse than missing file content.

     

    greetings from germany

    Chris