• Macbook: 128GB - 8GB free
  • iCloud: 200GB - 160GB free

I have a very frustrating problem. I have a 128GB Macbook so you can imagine how space is an issue. I bought 200GB iCloud storage thinking that would copy non-essential stuff to iCloud and free up space. I have PLENTY of iCloud storage left but it is no comfort because it does nothing to keep my MacBook free. It seems to keep about 8GB free.. which isn't quite enough to even download a new Xcode version.

I nearly bricked my MacBook by downloading a Mac osX update and it getting stuck half way through with "low disk space" issues.

Searching for large files shows these "iCloud Synchronization files" on my hard drive taking up valuable space!! But I can't unsync them and keep the file in the cloud. It appears I have no control over whats synced.

Is there a setting somewhere that says "try keep xGB free"? Or is there at least an "unsync" command on a synced iCloud file?

  • System Prefs>iCloud>Optimise Mac Storage. That's all there is. iCloud is not designed as real storage, only as a data synchroniser between iDevices.
    – Tetsujin
    Commented Mar 31, 2020 at 14:02
  • Yeah I've got optimize Mac storage on - it keeps about 3-4GB of iCloud files cached on my Mac that I don't know how to remove!
    – Mike S
    Commented Mar 31, 2020 at 14:05
  • tbh, you need another drive. The general rule about keeping 10% of free space on a drive doesn't really work when the drive is truly teeny. You really ought to be keeping 20 - 30 GB free at all times.
    – Tetsujin
    Commented Mar 31, 2020 at 14:08
  • 1
    What do you mean "general rule". I would love to keep 12.8GB free but every time I delete something, iCloud downloads more!!
    – Mike S
    Commented Mar 31, 2020 at 14:19
  • 1
    "iCloud can only re-fill the drive with things you have put there".. I suspect you are being deliberately obtuse, because you appear to be intelligent. If I put things on a drive, I put them on THAT drive, not simultaneously on my other drives - and especially not the small ones which necessitated the purchase of iCloud storage to begin with. There is no gaslightling in the world you can do to try convince anyone that iCloud filling up my drive until 8GB are left is somehow my fault.
    – Mike S
    Commented Apr 17, 2020 at 21:35

1 Answer 1


The answer for me is to turn OFF the Optimize setting (see image). It seemingly stopped filling up the harddrive after I changed that setting.

enter image description here

  • Is this still working for you? I just set up a new MacBook and when I untick this it starts downloading everything.
    – Seb
    Commented Dec 19, 2022 at 0:45

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