I recently created a file of just over 20GB and then deleted it shortly after, however my free space did not increase at all. I am using a 2012 MacBook Air with a 128GB SSD and I've had problems before with inaccurate free disk space (even when accounting for Time Machine's Local Snapshots). Usually though I can fix the problem by verifying the disk in disk utility, which then shows
Invalid volume free block count and
orphaned blocks errors, which I could then repair in recovery mode, but now disk utility repeatedly insists the volume is OK, and its S.M.A.R.T. status is verified.
I suppose I will have to just reformat the drive, reinstall OS X and restore from my backups, but is there anything else I can try first? Also, since this has happened a few times before (mainly when I delete a large amount of space in one go), should I suspect the SSD of having problems, in spite of its verified S.M.A.R.T. status?
UPDATE: I initially thought there was a 26.2 GB discrepancy. Interestingly though, whilst System Information reports that backups are taking up 12.65 GB,
sudo du -csh /.MobileBackups gives 31 GB. In total, this adds up to 94 GB of used space, which still amounts to a 7 GB discrepancy which I can't account for.