Amount of free disk space off by >100GB (on 200GB SSD!)

Discussion in 'macOS' started by segers909, Jan 19, 2014.

  1. segers909 macrumors regular

    Jun 7, 2009
    Hi everyone!
    There's a problem I've been struggling with for a while now: the amount of free disk space on my Mac is almost always incorrect. Right now, when I go into disk utility, it reports that there's 22,86 GB of free space on my 205GB SSD partition. I will then delete a 4GB file (and empty the trash) and the free space number stays the same.

    When I run a program like Diskeeper, (which gives an overview of what is taking up space on your drive), it'll scan my entire partition and then report that I'm only using 90.16GB!

    I've tried the obvious fix of using the "repair disk" feature in disk utility on both the drive and partition, and it's happened a few times in the last few months that disk utility detected "incorrect free blocks" and corrected it, but my free space will only go up by a few gigabytes. I brought my Macbook in for warranty, showing screenshots of disk utility reporting the incorrect free blocks. They've replaced my SSD, but now a couple of months later I'm in the same boat (and out of warranty).

    Does anybody have any idea as to what might be causing this? I'm quite desperate and willing to try anything at this point. I don't want to have to format every few months just to keep some free space on my SSD :(
  2. McGiord macrumors 601


    Oct 5, 2003
    Dark Castle
    If your are using TimeMachine and haven't done a backup recently there will be some local snapshots created that will occupy the space.
    Do a TimeMachine backup, or turn of TimeMachine or use the terminal to disable the local snapshots (search the forum or google it).


    Also run the maintenance scripts that normally run when you leave your Mac on overnight.
    Terminal again, google them.
  3. maflynn Moderator


    Staff Member

    May 3, 2009
    I believe Diskkeeper that the OP ran includes all files, including the local snapshots but to to be safe Download and use OmniDiskSweeper. It will provide a sorted list of what's consuming your space. I hate the interface of Diskeeper, with OmniDiskSweeper the result set returned is in more user friendly format imo.

    That's been unnecessary for a number of OSX versions now. Those nightly scripts if not run because the machine is off or sleeping will execute when the mac is turned on/woken up. They only archive the sys logs which normally shouldn't be too large, and if they were, would have shown up in his diskeeper exhibit
  4. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    It sounds like you have Time Machine turned on. Time Machine makes "local snapshots" that are saved in a hidden file. So when you delete files, they are placed in the hidden local snapshots folder and the disk space used shows the same in Disk Util.

    This space used is not shown in Finder, hence the different readings.

    Run this command in Terminal and it will show how much space is currently being used by local backups.

    sudo du -hs /.MobileBackups
    If this is what is going on, you can just ignore it. OS X will start to shrink the space automatically once your disk reaches 80% full.

    If it is bothering you, you can turn Time Machine off then back on again and the space will zero out.

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