Time Machine tells me it needs more backup space than my Mac HD is even using

Discussion in 'macOS' started by straks, May 14, 2011.

  1. straks macrumors newbie

    Feb 1, 2010
    Leuven, Belgium
    Got a strange problem here...

    On my Macbook Pro (6,1), i7 2,8Ghz, 8Gb ram, 500Gb HD i have Time Machine running to a network disk.
    OS X: 10.6.7

    All works well for a while, but suddenly i get a warning from TM, saying that it needs 178Gb of backup space to do a backup, and it doesn't have that much available.

    The funny thing is, my Macbook HD is only using 160Gb AND i have about 120Gb in the Excluded list.

    Only way i have found to fix this, is disabling TM, cleaning the backup drive (removing all files), rebooting my macbook, enabling TM and do a complete new backup.

    If i follow that procedure, it says (during backup): "Backing up ... of 37.38Gb", which is WAY more realistic (and actually about the size i would expect of a full new backup).

    So my question is: What is the cause of this problem, and how can i fix it without doing a full clean backup?

    I had to do this procedure three times in the last 2 months, btw

    *i searched the forum, but couldn't really find a similar problem, sorry if i missed it*
  2. MacmancUK macrumors member

    May 7, 2011
    Perhaps Time Machine needs twice the required space to backup before deleting ?

    I seem to remember this problem in another scenario, not using TM

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