External drive not showing in Startup Disk in System Preferences

TidBITS Talk
21

Thank you. But this has became so far removed from the original question which was:
On an iMac 2019 (Intel) with Mojave(10.14.6) installed on the internal SSD, the external Samsung T5 drive shows up on the desktop; but, not in the system preferences startup disk! Which means: the only way I can get Monterey to be the startup disk is to shut down completely, reinsert the external drive, and restart while holding the Option key. This is a pain like boot camp was. I have been working with Apple Senior Tier for 3 5-hour sessions so far. By the way, once in Monterey as the startup disk, the system preferences allows me to choose the startup disk (
but only if Monterey is the startup disk).

Thank you,
macntory@att.net

22

I think the original question has been answered. The Mojave Startup Disk preference panel doesn’t recognize Big Sur and Monterey system disks as bootable (probably because the boot code changed significantly since then), so it doesn’t present them on the list of choices.

I’m quite surprised the Apple tech couldn’t figure this out after 15 hours of work. In the worst case, he should have been able to create the exact same dual-boot system you’ve got and confirm the behavior.

1 Like
23

Thank you for the post-Big Sur information. How do you backup the Data volume?

24

Data volume is backed up just fine by current versions of SD and CCC.

The crucial difference compared to the way it used to be (Mojave and before) is that it’s now only Data that gets copied, not the whole system so the clone is no longer directly bootable*. But in terms of backing up your data, nothing has been lost. Anybody who has been using SD or CCC to back up their docs and apps, can continue doing so without a problem. Note also that in BS and beyond, System comes from the SSV so it doesn’t need to be backed up. Whatever you had before (provided it booted your Mac) was checked against Apple’s master copy (if that checked fails, you can’t boot it). So it doesn’t need to be backed up because it’s identical to a master Apple will install again from scratch whenever you choose.

*) In practical terms and for most people there is very little difference here thanks to the way iBoot offers the option to re-install the system and then have MA copy back all the Data parts. The only relevant difference here is if your internal partition becomes so hosed you can no longer boot at all (eg. on an M1 Mac). But as long as you can boot into recovery, you can still restore your system from a clone equivalent to the way it used to be. It’s how it’s done below the hood that has changed, for most cases there is little user-facing noticeable difference though.

25

If you use a backup utility like CCC, that’s what it will do by default. It will back up only the contents of the Data volume and ignore the System volume.

You need to take a few extra steps to make it clone the System volume (which will completely wipe the destination volume including any snapshots of older backups), but there’s no point in doing so unless you want to try and make a bootable backup, which is no longer recommended (and may not even be bootable on M1 systems).