View Full Version : Disk space going missing all the time

11th May 2010, 12:06 AM
My boot drive is regularly running out of space, but I'm not sure why. The only files going on here on a regular basis that I am certain are expanding the size are email/attachments, new apps and system files and maybe one or two docs a month. I know that when I commissioned this boot disk it had about 50GB usage. All music/video/image media is on external drives.

It's a 120GB drive, and at the moment reports 9GB free. However when I use OmniDiskSweeper to check what's taking up all the space, it only reports around 60GB in use.

Permissions and disk check are fine. I'm not inclined to believe the 9GB figure either because taking a look at this disk's clone (using SuperDuper) it reports only about 60GB used.

The first time I encountered this problem, I restored my entire boot disk from a Time Machine Backup and all the suspiciously used space was not restored alongside everything else.

This makes me think that some kind of temp file(s) is growing disproportionally large on a regular basis but is not being reported by the likes of OmniDiskSweeper.

Previously I have used terminal to trawl some of the system dirs like /tmp, /usr, and done command line size checks but nothing significant came up.

Any suggestions?

11th May 2010, 04:40 AM
The culprit is more than likely to be OSX itself. Not only will its background file-defragmenter lock out disk space when it is doing its thing (which is constantly) but you will 'lose' disk space to virtual memory constantly. Every app you open, every document you open, every tab in a brower you open, will be paged off to virtual memory on your boot volume.

Speaking of browsers, the worst culprit for this gobbling of virtual memory disk space is Firefox -- for every tab you keep open, Firefox will maintain a browser cache, and this persists between launches if you rely on Firefox's session manager feature.

And speaking of caches, OSX itself maintains several for its own use, and these need to be purged on a regular basis. Most times, OSX will 'rotate' logs and clean caches if left alone overnight, but sometimes it doesn't. Using a tool such as Onyx to force a cleaning of caches & logs might prove beneficial in your case.

11th May 2010, 07:26 AM
I have just solved a similar problem (although mine was caused by TechTool Pro) where the Protection Back-ups had swallowed up over 500GB of drive space!!!!
Just thought I would mention it as something else to check....although I am sure OmniDiskSweeper would have shown these files.

11th May 2010, 08:31 AM
Also, a sleep image file will gobble up HD space equivalent to your installed RAM.

11th May 2010, 04:54 PM
Are you sure the disk isn't partitioned? Or is the 120GB figure from the Finder?

11th May 2010, 06:26 PM
Check out this handy app.
Disk Inventory X (http://www.derlien.com/)

Might help you find out what is going on if its a file issue and not a partition issue

16th May 2010, 09:13 AM
On the 'working out where all the space on your HD went' front, I like and use GrandPerspective (http://grandperspectiv.sourceforge.net/).

It creates a coloured grid of boxes of different sizes representing the files. You mouse over boxes to see more details. And you can get size for whole directories.

Interestingly, the interface appears similar to 'Disk Inventory X'.
(Thought this is just a comparison from the screen shots on its site.)