MacOS – How to prevent conversion to APFS on High Sierra install

apfshfs+high sierramacos

The current understanding seems to indicate that "all SSD" machines will have at least their main/root file system converted to APFS on the install of High Sierra.

That means HFS+ is still a viable boot file system (as it was during testing the beta on an external rotational drive). I want to keep HFS+ for now.

How do I force a full default install, including Recovery HD, onto an "all SSD" MacBook Pro that keeps HFS+ as the only file system?

Best Answer

It should work by exiting any High Sierra installer GUI and starting the install from the command line:

/Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall --converttoapfs NO

Further install options can be obtained by using the --usage argument:

Arguments
--applicationpath, a path to copy of the OS installer application to start the install with.
--license, prints the user license agreement only.
--agreetolicense, agree to license the license you printed with --license.
--rebootdelay, how long to delay the reboot at the end of preparing. This delay is in seconds and has a maximum of 300 (5 minutes).
--pidtosignal, Specify a PID to which to send SIGUSR1 upon completion of the prepare phase. To bypass "rebootdelay" send SIGUSR1 back to startosinstall.
--converttoapfs, specify either YES or NO on if you wish to convert to APFS.
--installpackage, the path of a package to install after the OS installation is complete; this option can be specified multiple times.
--usage, prints this message.
--volume, path to the target volume.

Sources report that the command (in the Beta version) doesn't do anything on the first execution but on the second.

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