Size of Time Machine backup not as big as source?

Discussion in 'Mac OS X Lion (10.7)' started by Madvillain, Dec 2, 2011.

  1. Madvillain Guest

    Jan 15, 2008

    I just ran a time machine backup (to a time capsule), the first one on this drive. I am concerned it is not working properly. I have selected to exclude only my iTunes folder, leaving a backup size of 135 GB. The backup is complete, and the Sparse Disk Image Bundle size is 90 GB.

    Why is there a 45 GB difference between the size of what is supposed to be backed up and the backup?

    Thanks for any help.

  2. johnhurley macrumors 6502a


    Aug 29, 2011
    Compression probably? Backups can be compressed to save space ... not sure if Time Machine has a setting to enable/disable that feature.
  3. Madvillain thread starter Guest

    Jan 15, 2008
    Meaning I am losing data in my image files?
    That's no good.
  4. Partron22 macrumors 68020


    Apr 13, 2011
    No, if it were lossy compression, the elves would be hearing our cries of pain in Rivendell by now.

    Some of that 45GB could come from differences in block size between the two volumes. Some may come from the stripping of unneeded 'versions' of a file before it gets sent to the backup. Your older backups already contain some file versions, so there's no need to duplicate that data.
  5. Madvillain thread starter Guest

    Jan 15, 2008
    Looks like the reason is a 35 GB cache for Adobe Camera Raw.

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