MacOS – Large difference in reported free disk space

disk-spacehard drivemacbook promacosssd

I have a strange discrepancy in the amount of free disk space that's being reported.

The finder says:

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My iStat Menus says:

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Which is the same as df -h reports:

remco@Prosperpine ~  $ df -h
Filesystem                          Size   Used  Avail Capacity  iused   ifree %iused  Mounted on
/dev/disk0s2                       148Gi  127Gi   21Gi    87% 33479179 5383643   86%   /
devfs                              187Ki  187Ki    0Bi   100%      646       0  100%   /dev
map -hosts                           0Bi    0Bi    0Bi   100%        0       0  100%   /net
map auto_home                        0Bi    0Bi    0Bi   100%        0       0  100%   /home

Why would such a large difference occur? I've checked the disk using the disk utility and it does not report having any issues.

Specs: Late 2011 MacBook Pro 17", non-Apple Intel 160GB SSD, OSX Mountain Lion 10.8.2

Best Answer

Check the Storage section of About This Mac. You will probably see the missing 15GB listed there as "Backups". These are Time Machine local snapshots, and Finder ignores them when calculating free disk space, because they get deleted automatically when your free disk space drops below 20%. In other words, they give up their space automatically as needed, so the number in Finder is the one you should pay attention to.

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