OSX Tips

The  Storage  Display

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Effective with Lion 10.7.x, if you click the Apple icon at the left of your menubar, select About This Mac, then More Info on the window that shows, you'll see the Overview window of the About This Mac display:


 
Click the Storage button in the toolbar to see a (very rough) breakdown of the data on your internal HD and any externals:

Unfortunately, the categories are not explained, and can be very misleading.  There's no documentation of exactly what's counted in each category.

For example, Movies shows 287 MB on my test installation's Storage display (not shown here), but the Movies folder has just a couple of small clips, totalling 37 MB, so it must include video in other places, such as system folders and apps.

Apps also contains more than the entire size of your Applications folder.  So it apparently includes apps in system folders, too.  For example, on my small test installation, the Applications folder is 3.75 GB, but the Storage display shows 9.18 GB!

Audio and Photos are similar;  larger than what you see in your user home folder.

Backups are two different things: 

  1. •On a laptop's Startup drive (or a data drive) that's backed-up by Time Machine, they're Local Snapshots and aren't a problem, as they're temporary and will be deleted automatically if necessary.  But they're treated as free space by the Finder or Get Info, so those will show different amounts of free space than this display. See Time Machine FAQ #30 for details.

  2. •On an external HD, they're normal Time Machine backups (as in the second item in the sample).  Backups made by other apps are not included here, but will be in "Other."

Other is everything else:  all kinds of stuff.  Here's a partial list:

  1. •System Stuff:

  2. •The disk directory, catalogs, etc. that keep track of everything on the disk

  3. •The File System Event Store, a log of changes to the files & folders

  4. •OSX 

  5. •System work files (swap files, laptop sleepimage file, temporary files)

  6. •System caches and logs

  7. •Spotlight index

  8. •The Versions database (previous versions of various files & documents)

  9. •Files supporting various Apple apps

  10. •In each User home folder:

  11. •Preferences and settings

  12. •Downloads

  13. •User caches and logs

  14. •Word processing documents, spreadsheets, etc

  15. •Email and Contacts

  16. •Calendars

  17. •Browser history, bookmarks, cookies, web site icons

  18. •Keychains

  19. •Widgets

  20. •Data for any apps that doesn't fall into one of the categories above

  21. •Files supporting various apps


In addition, the categories are determined by Spotlight indexing, so if Spotlight isn't caught up, or you've excluded things from Spotlight indexing (via System Preferences > Spotlight > Privacy), the categories will be even less accurate.  For example, the 3rd line in the sample is a "bootable clone" of an OSX system, but it's excluded, so everything is shown as Other.

 


Thus, do not worry about the size of any one category, especially Other.

If the amount of free space seems too small, consider three things:

  1. •The folders you see in the Finder aren't everything on your system;  there are many system folders, some hidden.

  2. •If there's more than one user account on your Mac, one user (even an Admin user) won't see the accurate size of another user's home folder.

  3. •Time Machine's Local Snapshots are treated as free space by the Finder or Get Info.

If there's still more on your system than you expect, see Where did my Disk Space Go?