13 Replies Latest reply: May 15, 2012 12:25 PM by Pondini
whantk1 Level 1 (0 points)

I've been using an ext hard drive to back up my Mac with Time Machine, but now suddenly it

doesn't work. I get this message:

"Mac OS X can't repair the disk "My Passport". You can still open or copy

files on the disk, but you can’t save changes to files on the disk. Back up

the disk and reformat it as soon as you can. Files can’t be copied onto the

backup disk because it appears to be read-only."

The HD manufacturer's reformat instructions warn all files on the HD will be lost during reformat.

How can I reformat without losing any of the files backed up on my HD?


MacBook Pro, Mac OS X (10.7.3)
  • Steve-Gent Level 1 (0 points)

    Hi, I don't consider myself an expert but I might make a few suggestions.

     

    In Finder highlight the external drive and click File/Get Info (or CMD-I) to see what permissions are set on the drive.  It may say Read Only and you may be able to change this here (you might have to click the padlock icon and enter your admin password).

     

    Of course reformatting WILL erase all data on the disk but these are backups, right?  So that shouldn't be a problem.   If you do reformat, make sure you use the GUID Partition Table and Mac OS (Extended) Journaled settings.

     

    Hope this helps.

  • petermac87 Level 5 (7,365 points)

    have you tried rebooting holding down Command+R, booting into your restore partition and going to utilities, DiskUtility and repairing the External Disk and also repairing the permission on same Disc? You should find out quick if the disk is failing.

     

    Pete

  • Pondini Level 8 (38,740 points)

    whantk1 wrote:

    . . .

    How can I reformat without losing any of the files backed up on my HD?

    There's a chance a heavy-duty 3rd-party disk repair app, such as  DiskWarrior, can repair the backups.  These are expensive (DiskWarrior is about $100), and probably a good investment for the future, but there's no guarantee it will work. (If your backups are on an external HD connected to an Airport Extreme or Time Capsule, you must connect it directly to your Mac).

     

    If it can't fix your backups, or you don't want to spend the money, your only options are to erase the disk and let Time Machine start fresh, or begin backing-up to a different disk (you can still see and restore from the old ones, via the Browse option, per Time Machine - Frequently Asked Question #17.

  • whantk1 Level 1 (0 points)

    Thanks for the suggestion, but it won't respond when I try to change from read only.

    As far as losing all data during reformat, won't it be a problem because Time Machine will not work as designed, (i.e. not be able to go back to a specific date)?

  • whantk1 Level 1 (0 points)

    Pardon my ignorance. I'm not sure exactly where to use the Command+R to get to Disk Utilities

  • petermac87 Level 5 (7,365 points)

    Hold down those keys on restart.

     

    Pete

  • whantk1 Level 1 (0 points)

    Thanks. Do I do this with the ext HD plugged in?

  • petermac87 Level 5 (7,365 points)

    whantk1 wrote:

     

    Thanks. Do I do this with the ext HD plugged in?

    Yes. That is the disc you are wanting to test.

     

    Pete

  • Steve-Gent Level 1 (0 points)

    whantk1 wrote:

     

    Thanks for the suggestion, but it won't respond when I try to change from read only.

    As far as losing all data during reformat, won't it be a problem because Time Machine will not work as designed, (i.e. not be able to go back to a specific date)?

    Are you logged into your account as an 'administrator' and did you click on the 'closed' padlock icon in order to 'open' it (with your admin account password) ?

     

    If you reformat and start a new Time Machine backup you will lose older versions of files that have been edited but the new backup will create a copy of all the files (with a few exceptions) on your computer.

     

    Part of the problem here I believe (and I will stand corrected by the experts if I have this wrong) is in peoples expectations of Time Machine.  Generally TM initially creates one copy of a file on your HD on the destination drive.  If, over a period of time, you edit that file, TM will create a copy of the changes, each dated, which allows you to go back in time and restore an earlier version.  But only the current version exists on your computer (unless you are using the newer versions of Pages, Numbers, Text Editor etc which maintain automatic versioning but that is a whole other complex issue), so the earler versions stored in the TB backup are not really 'backups', in the sense that they are the only versions that exist.  TM has archived the versions, but only temporarily, because it may need to delete them at some time in the future to reclaim space (although I believe TM will warn you when it is about to delete a file).

     

    One has to ask the question..."If these versions are important to us, what the **** are we doing allowing only one version to exist?"   My take on the Time Machine is to consider it a backup of everything that currently exists on my computer.  If an older version of something is important to me I make sure a file of that version exists on my computer (or on a external HD which can be included in the TM umbrella) which will then be backed up by TM (and other backup routines), so I will always have at least two, probably three copies.

     

    Another question worth considering is.. "What if your TM destination drive died suddenly, without warning?" (they do) Then all those earlier versions would be gone instantly anyway.  There would be no discussion about 'Will I lose this? or 'Will I lose that?  So a good backup strategy is important.

     

    Still, I hope you can salvage your TM drive, so please let me know if you have any success.

     

    Regards

    Steve.

  • Steve-Gent Level 1 (0 points)

    Wow! Apparently I'm not allowed to say 'H.e.l.l.'

  • Pondini Level 8 (38,740 points)

    Steve-Gent wrote:

    . . .

    TM has archived the versions, but only temporarily,

    That's correct.  Since disk drives aren't of infinite size, older versions of files can't be kept forever -- Time Machine isn't a permanent archive.  While it varies widely depending on how you use your Mac, if you give TM 2-3 times the space of the data you're backing-up, it can keep old versions for several months, perhaps a year or more.  That's usually plenty of time to allow retrieval of files that were changed or deleted in error, or that got corrupted.

     

    The TM Prefs panel shows the "thinning" schedule:

     

    12a TM Prefs - thinning schedule.jpg

     

    (although I believe TM will warn you when it is about to delete a file).

    No, there's often no prior warning, and it's not file-specific.  Effective with Snow Leopard, you may see this warning, once, before it starts deleting old backups:

     

    C4  Lion disk near full warning.jpg

     

    If you have the Notify after old backups are deleted box checked in TM Preferences > Options, you'll be notified each time after old backups are deleted.

     

    See #C4 in Time Machine - Troubleshooting for details.

  • Steve-Gent Level 1 (0 points)

    Happy to be corrected by Pondini .  Apparently I gave TM too much credit.

     

    Still hoping the OP can regain access to his TM drive.

     

    Regards

    Steve.

  • Pondini Level 8 (38,740 points)

    Steve-Gent wrote:

     

    Apparently I gave TM too much credit.

    If you mean the lack of prior warning, there was one, when Time Machine first came out, with Leopard.  What's now a notification after deletions was a message before deleting old backups. 

     

    Apparently, too many folks didn't understand the message (the wording confused some), or just didn't respond to it, so TM kept waiting patiently for an answer, not making any more backups.  So Apple changed it when Snow Leopard was released.

     

     

    Still hoping the OP can regain access to his TM drive.

    Yup.  Doesn't sound good, though.