I’ve been running Catalina from an external Samsung SSD. I call it simply External 2. I have another, identical Samsung SSD for weekly backups, which I call External 1. I haven’t used the internal mechanical drive, which still runs Mojave, in a few years. Here’s the problem:
I connected External 1 and made a backup. No problem.
I unmounted External 1 but forgot to disconnect it.
I rebooted the Mac because I hadn’t done so in over a month (should have done it before backing up, but …).
When it rebooted, it took longer than usual and booted back to Mojave and simply mounted the two external drives as four drives (I guess one system drive and one data drive on each Samsung). Hmmm. Not what I had expected.
I restarted again, hoping to get the choice to select the startup drive by holding down the Option key. However, I was not presented with three bootable drives. I wasn’t presented with any bootable drive. The system simply booted again into Mojave. Again, not what I wanted.
This time I unmounted the backup drive (External 1) and disconnected it.
I restarted again and held down the Option key.
There was again no screen with a choice of drives to select, however the system did boot into Catalina (External 2), which is what I wanted.
PS. I tried selecting the Startup drive in System Preferences (highlighted External 2), but that got ignored during the restart in one of the earlier steps.
Can anyone explain this behavior? Is this a function of the way Catalina works (separate system and data drives)? It’s kind of freaky not being able to choose the correct boot drive. And does Option during restart no longer work as it once did?
Step 4. The taking longer than usual is probably the result of your startup disk preference (probably in NVRAM) not matching any available media, or not having any value set. So the system is going to wait for all storage devices to become ready, then pick one to boot based on an internal algorithm.
The fact that the non-booted devices appear as two volumes each (I assume System and Data) should not be surprising. The bonding process that combines them should only happen when you’re booting from the System volume in question.
As for why you don’t see any choices when booting with Option held down, I’m not sure. I see it on my 2018 Mac mini.
If you haven’t already done so, check the startup security utility. If your system is configured to restrict what you can boot from, it might be getting in the way.
The weirdness may also be due to the fact that Mojave boots from a single storage volume, while Catalina uses two bonded volumes (System and Data). Switching between them may be messing up your Startup Disk preference in a way that’s causing problems. Or the code launched by an Option-boot (not sure if this is in the Boot ROM or your Recovery partition) may be getting confused by a mix of systems involving different boot mechanisms.
Thanks. This is Intel. Machine is from early 2014. Has a 1TB internal drive.
Yes, not seeing any choices is something I haven’t seen before.
Also, this is a system without a T2 chip, so there is startup security utility that I am aware of.
Interesting that unmounting and disconnecting the backup drive (External 1) allowed the system to boot “normally” into my working Catalina drive.
As an aside, I do recommend keeping a wired keyboard at home and in the office. New ones can be purchased for 10-20 USD, and it’s not hard to find used ones for free or close to it. If a situation arises where you need one for troubleshooting, it’s great to have one handy rather than spending time and effort running to a nearby store that may or may not have one in stock, etc. The same goes for a wired mouse, too.
Bluetooth keyboard. That idea never crossed my mind. I had assumed it worked identically to all the other keyboards I have had in terms of key functionality.
Sage advice. I wanted to boot into Safe Mode by holding down the Shift key. It just wouldn’t work. It’s a rather old Apple Bluetooth keyboard, but the Shift key is apparently OK, at least in apps (and this post!). Fortunately, I have an ancient, wired keyboard that booted into Safe Mode just fine.
Although it has worked on many other occasions, I do not know why the Bluetooth Shift key did not work this time ‘round, whereas the key is fine otherwise.
Yes, my conclusion has been that bluetooth access for keyboard & mouse isn’t activated until several steps after the system begins starting up, too late to affect the selection of which macOS install to boot with.
I’m wondering if the Magic Keyboard works for startup keys if it is plugged into to a USB port with its charging cable.
I never did that before, because a) I was using that Lightning cable to connect to an iPhone unless I needed to charge the wireless keyboard, and b) I still have the older Apple non-wireless keyboard plugged in all the time so I just press the option key on it.
(The only reason I’m using the wireless keyboard at all is because of COVID-19. I started working at home more, and since my job is mainframe programming I use the function keys a lot. The wireless keyboard has larger function keys than the older USB keyboard.)
I was just going to post this - yes, it does. I have done this many times on my 2019 iMac. (I leave the keyboard plugged in all of the time except when I need the lightning port for something else - usually charging the mouse.) In fact, Apple suggest this here.
If you’re using a wireless keyboard, plug it into your Mac, if possible.
I have USB-A ports on this iMac, however. Would that make a difference? Also, wouldn’t keeping it plugged into a USB port all the time overcharge the keyboard? The only time I plug it in is when the battery level is low.
You might need a different cable or a USB hub, but it should still work. I still use a wired USB Apple keyboard on my 2018 mini, which is connected via a generic USB hub.
No. The keyboard, like all modern chargeable devices, has a charging circuit which will stop the charging when the battery is full.
An old USB-A to Lightning cable will work. All internally rechargeable Magic devices (as opposed to the ancient removable battery versions) shipped with cables appropriate to their generation. I always keep one of those cables plugged into the computer so that when the time comes to recharge it, I can easily plug it into any device.
OK. With the Bluetooth keyboard connected via the USB cable to the iMac (the charging cable), the Option key worked. Bluetooth mouse didn’t seem to work though. However, that does prove your point. Interesting as this behavior is something I never would have expected.
The keyboard becomes a USB keyboard when you plug it in (rather than a BT keyboard). When I unplug the keyboard I get a notification almost right away on the iMac that the keyboard has connected to Bluetooth.