Mystery 8gb has disappeared from my hard drive! -Screenshot

[FortunesFool]

Fairly straightforward query here - I have an old 120gb that came with my mbp, so every gb counts. Formatted size is 111GB, and when I add up all the files on my disk, it comes to ~97GB. However, when I look in the info about the drive, it says I'm using 105GB. I like to think of myself as pretty knowledgeable when it comes to macs (got my first mac in '92), but I can't figure this one out.
I do download a lot of stuff frequently and offload it to externals, but I've never had a phantom block of space this large disappear before.


Any ideas? Preferably one that didn't involve restarting or running onyx as I don't particularly like quitting applications, but if that's the only solution then I'll take it.

 

[sickmacdoc]

Well, the first thing that comes to mind is that the numbers in a finder window like you have attached will never add up to the total space used because of the multitude of system files and caches that are invisible to that view.

Perhaps downloading the free pair of utilities Disk Inventory X and GrandPerspective which both show you the contents of your drive graphically will help point out some large invisible cache or log files that will help explain the discrepancy.

 

[Guiyon]

Assuming you're doing your addition by adding all the sizes in the "Size" column; you're not adding up all the files! There are several, system critical, invisible folders at the root of the drive (/usr, /var, /bin, ...); these can take up to several GB depending on your install. In addition, you may also have some swapfiles hanging around and/or a sleep image file (this can take several GB as well).

 

[FortunesFool]

I'll check out those two programs and see if I can figure anything out.

Thanks!