mac high sierra updates not installing on raid hd

This has become more complicated with the advent of the T2 chip and its secure boot, but one of the advantages of the M1 Macs, so we thought, was their ability to boot from a sealed system on an external disk without having to alter security settings. If your Mac won’t start up properly from its internal disk, you may well be able to get it up and running from your external disk, which you can keep armed with diagnostic and repair tools for such emergencies. It’s been one of the favourite recovery tools for many Mac users going back for more than a couple of decades. There are plenty of good reasons for wanting an external bootable disk, of course. (Note that this isn’t about creating a bootable installer for Big Sur, which is widely documented now.) I wish this article could explain how to do it successfully, but like many other M1 owners, all that I’ve tried so far has failed.

If your Mac happens to be one of the new M1 models, then you may find this tricky, or even impossible. It’s one of those commonplace tasks: installing a bootable version of macOS on an external disk.

Mac high sierra updates not installing on raid hd