I foolishly bought a Mac Mini with 128gb internal SSD for compiling Unity games for iOS, thinking "all I need to install is Xcode and Unity, and I can put documents on an external drive". However, macOS eats up about 45GB, Xcode will quickly eat up another 40GB and continue to grow without end, and Unity uses up a few more GB. You need about 40GB of free space to upgrade macOS and about 25GB of free space to upgrade Xcode, meaning that you quickly end up in a situation where there isn't enough free space on the Mac to upgrade anything. One time I cleared up exactly enough free space to upgrade macOS with nothing to spare, then the upgrade ran out of space and failed mid-upgrade (apparently the "required free space" is not accurate). This completely broke the OS and I had to erase everything and reinstall from scratch.

Having run into the "not enough space to upgrade" issue yet again, I'm ready to give up and try something different. Since macOS can be installed on an external drive, I'm thinking I'll reverse the usual strategy - I'll install the OS and applications on the external drive and save documents on the internal drive.

Normally Xcode can only be installed on the internal drive. If macOS is installed on an external drive, will xCode still be installed on the internal drive, or does it install to the same drive as macOS?

1 Answer 1


Apps from the Mac App Store like Xcode install to /Applications which maps to the Applications folder on the data volume in the same container as the macOS installation. This can be moved wherever you desire after installation, but it sounds like this is the location you want anyway.

Xcode from developer.apple.com is the .app bundle inside a compressed archive. You can download, extract and move the app wherever you desire.

  • There's a lot more to Xcode than just the .app bundle. The Xcode cache can quickly grow to tens or even hundreds of gigabytes of files (e.g. device support files, simulators, compiled application bundles, etc). Moving Xcode in its entirety is somewhere between difficult and impossible; see e.g. stackoverflow.com/questions/59159232/…
    – user45623
    Mar 25, 2021 at 21:43
  • @user Xcode is the app bundle. Its temporary files, archives when you build a project, etc., are not and should not be considered part of the app. For example, text documents or temporary files created with a word processor should not be considered part of the app bundle.
    – grg
    Mar 25, 2021 at 21:45
  • @user45623 Xcode also loads stuff elsewhere - in ~/Library and /Library. But it does what you want. Except for your projects, everything is on the boot disk.
    – Gilby
    Mar 25, 2021 at 21:58
  • @Gilby What I want is to install Big Sur on the internal drive and put everything else on the external drive, but since this seems infeasible, I guess I'll do OS and apps on the external and documents on the internal.
    – user45623
    Mar 25, 2021 at 22:31
  • @user45623 what is your drive configuration (types and sizes)? I am guessing you have an internal HDD and an external SSD.
    – Gilby
    Mar 27, 2021 at 22:28

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