External SSD will not restart, reverts back to internal HD

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Level 1

4 points

External SSD will not restart, reverts back to internal HD

I have cloned my internal HD to external SSD connected thru USB3 port, and it starts and runs fine using Startup Manager (hold Option key). However, whether selecting the external drive from Startup Manager (using Control key), or from Startup Disk in Sys Prefs — it reverts to the internal HD on restart. No firmware password, No T2 chip. Late-2013 iMac, so only able to run Catalina - but, it is up to date. How do I get it to ‘stick’ on the external startup disk?

iMac 27″, macOS 10.15

Posted on Feb 4, 2022 7:41 AM

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Answer 1

Texan2 Author

Level 1

4 points

Feb 4, 2022 8:06 AM in response to PRP_53

Thank you. Assuming that works (it hasn’t yet in many attempts), it won’t fix an unattended restart, nor a start after power outage, etc. My goal is to run from the external for performance, to extend the life of this old Mac. So, I want it to stick with the external automatically, without having to be there to hold Option.

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Answer 2

PRP_53

Level 10

91,681 points

Feb 4, 2022 9:44 AM in response to Texan2

Texan2 wrote:

OK, that did work (I unplugged a second external SSD bootable clone). Question: when installing an OS update, at start manager, do I select the external, or the added macOS bootable?

" Question: when installing an OS update " as in Security Update 2022-001 for Catalina ?

I would disconnect all External Drives including the Clone(s) and apple the update to Internal Drive from Safe Mode

Test how the updated is working on the Internal Drive. Once satisfied it is work without issue presenting than make New Clone(s). Doing this way will protect the system incase the updates does not work well or need to revert back from the existing Known Working version of Catalina.

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Answer 3

Feb 4, 2022 10:44 AM in response to Texan2

Texan2 wrote:

My goal is to run from the external for performance, to extend the life of this old Mac. So, I want it to stick with the external automatically, without having to be there to hold Option.

just go into SystemPreferences > StartupDisk,

then choose the external drive as the startup drive. (Catalina 500 GB is my external)

then the machine will boot into your external drive every time after a restart or auto restart after a power outage, etc. if you ever need to boot into the external, then hold the option key during boot as you are currently doing to boot to your external drive.

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Answer 4

Feb 4, 2022 10:57 AM in response to Texan2

Texan2 wrote:

Question: when installing an OS update, at start manager, do I select the external, or the added macOS bootable?

when you start to apply an update / upgrade, whichever drive you are booted into at the time becomes the default boot drive. if you update / upgrade the internal, for example, you will have to manually reset the external drive as the startup drive AFTER updating / upgrading the internal.

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Answer 5

Texan2 Author

Level 1

4 points

Feb 4, 2022 11:00 AM in response to jeffreythefrog

Right. That was what wasn’t working. I would set the external as Startup Disk and click restart — it would ask (twice) for password to unlock Startup Disk, even though I had already unlocked it, then commence restarting - to the internal HD. And going back into Startup Disk, it still said External (but, had booted to the internal).

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Answer 6

Feb 4, 2022 11:04 AM in response to Texan2

ok, i've never tried restarting after setting the startup drive using the "restart" button in "startup drive". after selecting the drive, i lock the panel, and exit out of startup disk. then restart the machine with the apple menu restart option. i don't know if that will make a difference, but maybe try that if you haven't already.

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Answer 7

Texan2 Author

Level 1

4 points

Feb 4, 2022 11:27 AM in response to jeffreythefrog

Agree that’s how it ‘should’ work; but, instead, with it booted into the external, the update started then, during its automated restart, reverted to internal HD. Which was ‘confused’ because it hadn’t started an update. I looked at startup manager to find an additional Mac startup image - and wondered if that wasn’t what the update process should’ve booted from. Anyway, I will try keeping the second external SSD unplugged, and see if it fixes the issue. Thank you for replying.

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Answer 8

Texan2 Author

Level 1

4 points

Feb 6, 2022 2:46 PM in response to Texan2

Update: the problem was solved by unplugging one of the two bootable SSDs. Tested on both SSDs separately - functions correctly on both. As long as I run only 1 USB external - the system keeps restarting to the external as expected. In fact, it is performing an update installation now - with the multiple restarts - all to the external. Very grateful to you both.

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Answer 9

PRP_53

Level 10

91,681 points

Feb 4, 2022 7:49 AM in response to Texan2

Have ONLY the Bootable Clone Directly connected to the computer and Option at restart.

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Answer 10

PRP_53

Level 10

91,681 points

Feb 7, 2022 2:21 AM in response to Texan2

You are welcome and thank you too.

Do come back to the ASC Forums, in the future, if / or when additional question may arise

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Answer 11

Texan2 Author

Level 1

4 points

Feb 4, 2022 8:35 AM in response to PRP_53

OK, that did work (I unplugged a second external SSD bootable clone). Question: when installing an OS update, at start manager, do I select the external, or the added macOS bootable?

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