I have a Mac Book Pro, first generation. It is running 10.6.4. I usually keep it running. I put it into hibernation mode (i.e. it writes the state to disk and powers down) when I need to put it to sleep.

I have a ~100GB hard drive. Now I only have about 3.5 GB free. I've noticed that recently i get the low disk warning quite a bit and when I check sometimes it dwindles down to a few MB. I figured that it might have been my browsers (Chrome, Safari) caching stuff. I clear the cache and it frees up some space. But I never get back to 3.5GB.

So, I decide to shutdown and restart. Every time I do that I see that indeed I get back to about 3.5GB free.

My question is how do I figure out what is slowly eating up my disk space? Have people out there experienced these symptoms? What was the cause and how did you deal with it?

2 Answers 2


It’s a combination of the page file (virtual memory) and the hibernation file that gets written when you put your computer to sleep. Of course, other processes may also leave temp files that get deleted when you restart. There isn’t really much you can do to improve that without affecting your computer’s performance.

You can get a utility like WhatSize, Daisy Disk or similar to visually inspect the contents of your hard drive and see where is the “abnormal” file or directory.

You can also use Monolingual to reduce the size of your executables and remove unwanted languages and files.


The virtual memory file is located in


and the hibernation/sleeping file in


Please not that you can’t (and shouldn’t) delete the vm file while OS X is running.

  • How can I check to see if they are indeed the Pagefiles and the hibernation file that eats up the space? Where are they located?
    – milesmeow
    Sep 7, 2010 at 2:48
  • Please note that you just can’t delete those, you have to make more room. OS X is memory intensive and uses the storage to cache a lot of stuff to make things work smooth. You need a new drive or you’ll have to delete stuff. Windows (specially vista and 7) would suffer the same problem as any other modern OS. Sep 7, 2010 at 22:02

That is an accumulation of virtual memory and caches. The system will gradually consume a decent amount of disk space to perform optimally. This is akin to the scratch disk in Photoshop.

The only way to reclaim it is to shut down and restart. I would not go deleting page files or cache files in use by the system.

You shouldn't be running with 3 GB free. Move some stuff around, compress things you use rarely, and delete stuff that is just taking up space. Try to run with at least 10 % free if possible.

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