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Time Machine could not complete the backup.

22583 Views 45 Replies Latest reply: Jan 17, 2014 11:34 AM by TinMass RSS
  • Michael Prewitt Level 1 Level 1 (15 points)

    I, too, have had this same error/problem since upgrading to Mountain Lion, the "Files can’t be copied onto the backup disk because it appears to be read-only." error. (Previously I was using Lion, and before that Snow Leopard. I never had this problem under either of those OS versions.) In my case I'm backing up to an external 4GB Western Digital drive using FireWire.

     

    Disk Utility reports no errors with the backup drive. Unmounting and remounting the drive corrects the issue, but it has happened twice to me now, and based on the above comments I'm expecting it will probably happen again.

  • DavidWhelan Calculating status...

    Same problem here - Disk Utility shows no errors then a few days later, TM complains disk read only.

  • Doctor Tech Calculating status...
    Currently Being Moderated
    Nov 9, 2012 11:59 AM (in response to DavidWhelan)

    The 2 times i've noticed this problem is immediately after I have repaired the disk permissions. For whatever reason I get this feeling that once a particular permission is repaired, the TM drive won't be recognized properly. This is a huge pain in my ***! This time I will try unmounting and mounting it back, but last time I had to erase my entire drive of backups and start over...

  • Pondini Level 8 Level 8 (38,710 points)
    Currently Being Moderated
    Nov 9, 2012 12:24 PM (in response to Doctor Tech)

    Repairing permissions doesn't touch your backups.  It only touches system files and files installed by the OSX installer (ie, on your startup drive).  See About Disk Utility's Repair Disk Permissions feature.

     

    There's no reason to repair permissions unless you suspect a permissions problem. 

     

    Did you do anything else at the same time? 

  • cavenewt Level 2 Level 2 (335 points)

    Disk Utilty can't read the SMART (self-monitoring) characteristics of an external drive, so DU can't tell you if the drive is bad. In any case, DU is worthless if the failure is of bad blocks (sectors).

     

    Has anyone with this problem tried a block scan with TechTool Pro? or repaired it with Disk Warrior (which will throw little comments about "disk malfunction" if there are bad blocks)? Does your System Log contain any references to "I/O error"?

     

    Drives go bad all the time (ALL drives will fail eventually). Perhaps Mountain Lion's TM is more sensitive to disk problems than previous versions, which would be a Good Thing in that you would have more warning of a disk failure than if it was to suddenly go belly-up.

  • wbowles Level 1 Level 1 (0 points)
    Currently Being Moderated
    Dec 24, 2012 6:41 AM (in response to Steve Johgart)

    Not sure if this is the right place but, I have an external La Cie usb/firewire drive (500gb) as a Time Machine drive (on the USB connection).

     

    It seems to back up ok but today it failed to mount once, so I figured I'd run Disk Utility but when I choose the drive (not the partition), both verify and repair are greyed out.

     

    When I select the partition, both Verify and Repair are available so I decided I'd verify first but after about an hour it had only checked at best 10% of the drive, so I cancelled.

     

    Late model (2011) 21.5inch 2.5 GHz Intel Core i5. Lion 10.7.5

     

    B

  • Pondini Level 8 Level 8 (38,710 points)
    Currently Being Moderated
    Dec 24, 2012 8:33 AM (in response to wbowles)

    wbowles wrote:

    . . .

    figured I'd run Disk Utility but when I choose the drive (not the partition), both verify and repair are greyed out.

    That's rather odd.  Effective with Lion, that should verify/repair the partition map (just takes seconds). 

     

    Try ejecting, disconnecting, and powering the drive off for a few minutes.  Restart your Mac, then reconnect and power the drive on and try again.

     

    If that doesn't help, please post a screenshot of the Disk Utility window -- perhaps a clue is lurking there.

     

    When I select the partition, both Verify and Repair are available so I decided I'd verify first but after about an hour it had only checked at best 10% of the drive, so I cancelled.

     

    It makes no sense to Verify first - - if that finds a problem, Repair has to repeat the entire process.

     

    Just run Repair Disk; yes, it will take quite a while, depending mostly on how many backups you have, and the time estimates will vary as it completes each stage.  It will be longer if it's finding things that need repair, as it may have to repeat some steps.

  • cavenewt Level 2 Level 2 (335 points)
    Currently Being Moderated
    Dec 24, 2012 8:42 AM (in response to wbowles)

    As Pondini said, repairing a TM disk can take a while. Be patient.

     

    That said, if the drive is failing with bad blocks, that iwll also cause delays, as reading each bad block will have to time out before it can move on to the next. Since it's an external, about the only way to test it for sure is to do a block scan with something like TechTool Pro, which will also take a long time.

     

    Another way is to clone the drive with Carbon Copy Cloner; if there are bad blocks, you will see I/O errors in the CCC log.

     

    You could also examine your system log for I/O errors.

  • wbowles Level 1 Level 1 (0 points)
    Currently Being Moderated
    Dec 24, 2012 9:19 AM (in response to Pondini)

    I'll try your suggestion re powering down etc.

     

    tried placing a screenshot but no go.

  • wbowles Level 1 Level 1 (0 points)
    Currently Being Moderated
    Dec 25, 2012 12:45 AM (in response to cavenewt)

    Well I finally got DU to work and the disk seems to be ok now but I still can't check the drive (not the partition).

     

    B

  • Pondini Level 8 Level 8 (38,710 points)
    Currently Being Moderated
    Dec 25, 2012 7:40 AM (in response to wbowles)

    wbowles wrote:

    . . .

    tried placing a screenshot but no go.

    What do you mean?

     

    Assuming you're able to make a screenshot, click the camera icon in the toolbar at the top of the editor box to select and post it. (Sometimes it won't work the first time; cancel and try again).

  • wbowles Level 1 Level 1 (0 points)
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    Dec 25, 2012 8:55 AM (in response to Pondini)

    Screen Shot 2012-12-24 at 17.16.23.jpg

  • Pondini Level 8 Level 8 (38,710 points)
    Currently Being Moderated
    Dec 25, 2012 9:08 AM (in response to wbowles)

    That's very strange.  The only thing I can see is, it has the Apple Partition Map (at the bottom), not GUID.  GUID is the default for an Intel Mac, and preferred, but as far as I know, Disk Utility should be able to repair it's partition map.   I don't have a disk set up that way, or one I can test with, so I can't be sure.

     

    The ability to repair the partition map was new with Lion, so it's possible Apple didn't include repairing an APM map.  Disk Utility's help is pretty skimpy on the point (it talks about repairing the "disk's formatting information"), and I can't find any other documentation either way.

     

    But since the partition itself checks out ok, the disk is probably fine. 

     

    If you ever have to erase it, you might try reformatting it, and use the GUID setup. 

  • wbowles Level 1 Level 1 (0 points)
    Currently Being Moderated
    Dec 25, 2012 9:30 AM (in response to Pondini)

    I don't see that option when select Erase and the disk was formatted with this Mac.

  • Pondini Level 8 Level 8 (38,710 points)
    Currently Being Moderated
    Dec 25, 2012 9:37 AM (in response to wbowles)

    Sorry, I guess I wasn't clear.   You don't see that on erase, but you do on reformatting.  

     

    See the blue box in Time Machine - Frequently Asked Question #5 (the Options button).

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