While I was running a macOS Support Essentials 10.13, one of my delegates asked "Is it possible to prevent conversion to APFS when upgraded to High Sierra?" After explaining to him, I realized that most of the room did not realize this was an option, so I thought I'd share it better.
As most of you will know as part of the MacOS High Sierra upgrade / install process, the installer will convert SSD (Solid State Drives) drives from using the HFS + (Mac OS Extended) file system to the new default file system APFS (Apple File System), Rotation Drivers and Merger Drivers, are not automatically converted.
If you are one of Mac administrators who do not, I do not want to convert, there is a way to install MacOS High Sierra OS on, and skip the APFS conversion. Apple, as part of the installer, includes a command-line tool called startosinstall.
startosinstall has a number of options, one of which is the option -converttoapfs which can be used to prevent / force the conversion to APFS.
AmsysBlog: ~ ladmin $ / Applications / Install macOS High Sierra.app/Contents/Resources/startosinstall -converttoapf NO
There is also a -nointeraction flag, it is not listed in the documentation, which automates the installation by suppressing all user interaction, including the -agreetolicense switch.
If you want to install to another volume, you can add volume
AmsysBlog: ~ ladmin $ / Applications / Install macOS High Sierra.app/Contents/ Resources / startosinstall -converttoapf NO Volume / Volume / External
I hope you found this useful and welcome you to comments. MacOS Support Essentials 10.13 is a great way to get into the weed and improve your Mac support skills (and you can download an Apple Certification). If you are interested, please send us a line at firstname.lastname@example.org