Time Machine Not Overwriting Backups

Discussion in 'Mac OS X Lion (10.7)' started by AppleDev879, Dec 28, 2011.

  1. AppleDev879 macrumors newbie

    Mar 1, 2011
    Hi all,

    I've got a 1TB external drive connected via USB to my 1TB iMac, which I use for Time Machine. I have 93.9 GB left on the internal disk. But when Time Machine goes to make a backup, it informs me that it does not have enough space to make a backup regardless of the fact that the drive is empty and used solely for Time Machine. It is my understanding that Time Machine needs a little extra space on the disk for organizational purposes, but it doesn't seem like it should need over 90 GB! I've tried erasing and reformatting the disk in Disk Utility, but still no luck. I'd also found that prior to reformatting, Time Machine would not delete old backups from the disk. Any help would be greatly appreciated. Thanks again.
  2. nippyjun macrumors 65816

    Jul 26, 2007
    I do believe that you need a larger drive to backup your 1tb drive.

    Do you have another external drive that you can temporarily move some of your data to to see if time machine works with less of your internal drive filled up.
  3. Krazy Bill macrumors 68030

    Krazy Bill

    Dec 21, 2011
    Now *why* would he need an external drive with more capacity than than internal one?
  4. waynep macrumors 6502

    Dec 31, 2009
    I think I read somewhere that the recommended size for a Time Machine drive was 2x the drive you are backing up, but I can't fine that link now . . . .
  5. mstrze macrumors 68000

    Nov 6, 2009
    Because Time Machine allows you to go backwards in 'time' to recover files and the state of your drive from days, weeks or months ago. Hence, at some point you WILL have a TM partition that is larger than the amount of stuff on your internal.

    The rule of thumb I had always heard is 1.5 times the size of your internal drive when looking for a drive to use with Time Machine.
  6. thundersteele macrumors 68030

    Oct 19, 2011
    It is recommended that you use a drive that is bigger than your internal drive for backups. But it's not mandatory.

    What is the actual size of the backup drive, after formatting? Can you delete some stuff on the internal drive, or move it to some other storage space?

    Currently you can't really benefit from Time Machine, so you might as well manually back up to the external drive or use a different tool to create a copy of your internal disc on the backup drive.

    Also, with USB 2.0, this might take a day or so to finish.
  7. AppleDev879 thread starter macrumors newbie

    Mar 1, 2011
    Thanks for your help. That's disappointing.
  8. Martyimac macrumors 68000


    Aug 19, 2009
    S. AZ.
    Not sure the other posters are correct. When I had my MacPro, I had a 1TB HD and a 1TB backup disk. Time machine worked just fine and I never had issues with running out of space. Now, granted my system disk was never more than 50% used but my TM disk only had about 20% filled up.
    I would continue to look for other issues.

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