Time Machine - suddenly back up's fail...

Discussion in 'iMac' started by GilesM, Apr 2, 2011.

  1. GilesM macrumors 6502

    Oct 17, 2008

    I have been using an external hard drive as my time machine for years, then suddenly the back ups started to fail.
    So I went in to Time Machine settings and found that the reported size of the next back up was greater than space that existed on the drive, then I noticed something odd, my Imac has an internal HD of 250GB of which 94GB is used.
    However the next back up had a reported size of 490GB!

    All my external drives (one for iTunes, one for video content) are excluded, and yet the estimated size of the back up is 490GB from a 250GB drive...

    So, I erased the drive, so now it's empty and ready to take a back up, but with such a huge estimated size it will not fit...

    Any ideas why suddenly Time Machine thinks there is 490GB to back up from a 250 GB system drive with only 94GB used?
  2. QuarterSwede macrumors G3


    Oct 1, 2005
    Colorado Springs, CO
    Did you try turning off TM then back on the see if it would try to recalculate again?

    I had a similar problem a while ago where TM filled up and refused to delete the old backups. Luckily, for me, a wipe of my external TM partition did it the trick.
  3. GilesM thread starter macrumors 6502

    Oct 17, 2008
    yep, tried that. I have performed a couple of re-boots of the imac (with and without the time machine drive attached) no luck....

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