I came from OSX Mavericks, and since the update to Yosemite I gained 20+ Gigabytes of space. I would usually expect to lose space. Did the update delete some files that I am not aware of?

  • you mean it removed the bloatware?
    – Ruskes
    Oct 20, 2014 at 23:42
  • I am not quite sure what it removed. It is possible that it removed cache files from Mavericks. Oct 21, 2014 at 13:07
  • Same thing happened to me - around 20G more after install free. I back up only to external devices. I haven't found anything missing and I've gone looking. This may be a first for any OS upgrade!
    – waaronw
    Oct 28, 2014 at 18:09
  • @Buscar Could you expand on what 'bloatware' you are referring to?
    – grg
    Oct 28, 2014 at 18:17

2 Answers 2


As you know OS makes a lot files during its uses.

Many of those are hidden files or Cache or Temp files but all related to the specific OS.

When new OS is installed it takes over those (deletes most of them) and starts making its own ones.

For example the Terminal command

open $TMPDIR../C/

will show you the cached files/folders, but this will only show the non hidden ones. I have some 3 Gig of stuff in there.

OS will hide system files and ones it creates in due process to protect them, but they can be made visible if one wants to do that.

I can not say what specific files new OS install will remove but they must be specific to a previous OS and no longer needed by new OS since it will create its own versions of them.


Could it be that installing Yosemite "purged" backups prepared when you were still on Mavericks? It did that with my machine at least.

It could be that as part of the upgrade process, backups prepared on the previous OS version are pruned.

Apple's KB on the minimum requirements for OS X Mavericks states:

Your Mac also needs:

  • OS X Mountain Lion, Lion, or Snow Leopard v10.6.8 already installed
  • 2 GB or more of memory
  • 8 GB or more of available space

The Wikipedia page for OS X Yosemite indicates the systems need approximately the same amount of free space:

All Macintosh products capable of running OS X Mavericks are supported by Yosemite; as with Mavericks, 2 GB of RAM, 8 GB of available storage, and OS X 10.6.8 (Snow Leopard) or later are required. However, the system requirements in order to take full advantage of the features of Handoff include a Mac with Bluetooth LE (Bluetooth 4.0), and other currently unknown factors.

So unless you're noticing some pretty big files missing, I don't think difference in OS size can account for the freed-up space. Given that your system is behaving normally, I'd say Mavericks TM backups were deleted as part of the Yosemite installation process.

  • What exactly do you mean by "backups"? Do you mean old cache files from Mavericks? Oct 21, 2014 at 13:08
  • no, OS X generates backups for when they are ready to be transferred to an external HDD when one is plugged. These are Time Machine backups. If you got to About This Mac → Storage, you can see how much they're currently taking up.
    – zerohedge
    Oct 21, 2014 at 20:41
  • And for us not using TM backups, but still got around 20GB freed after Yosemite upgrade?
    – Wrench
    Oct 22, 2014 at 10:46

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