ISSUE: My Mac is showing less free hard drive space than I am currently using?
If you turn on the show sizes option in MacOSX
Finder > View > show view options >
calculate all sizes
the total folder sizes dont match that of the reported drive free space
further research showed that (among other things)
private/var/vm/sleepimage taking up too much space. (equal to the system ram in the laptop)
RESOLUTION:
Check if you have Trend Smart Surfing installed that the log files are not growing too large
/private/var/logs/TrendMicro/TmLoginMgr/*
otherwise you can disable safe sleep mode (ie hibernate)
Run the following in a terminal session, reboot and then delete the file
$ sudo pmset -a hibernatemode 0
$ sudo nvram "use-nvramrc?"=false
reboot
sudo rm /private/var/vm/sleepimage
This does however mean that if the power cuts to the device while its sleeping - all work is lost.
Handy for laptops to keep this option on.
UNDO:
to reenable change to 3 and =true
done!