startup disk recognition

Question

startup disk recognition

Running an iMac from November 2015. Added SSD drive to USB 3.0 ports on the back. Transitioned in to Monterey by Adding a container. Was able to boot from either Mojave or Monterey for over a year. [on the external SSD] Now the Mojave side doesn't want to recognize the Monterey side as a startup disk. Whether done thru system preferences or done with the option key on start up. Monterey side will recognize Mojave. The importance of being able to boot with either side? iTunes and Banking.

If there is a FAQ on this please send the link.

Been running Mac since my '88 Mac SE. This one has me stumped.

-wes

iMac Line (2012 and Later)

Posted on Jun 4, 2022 6:03 AM

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Answer 1

Jun 6, 2022 8:46 AM in response to Owl-53

Both Monterey and Mojave installed just fine on an external SSD attached to a computer who's hard drive contained Mojave. [separate containers]. Both ran for over a year. Then the Mojave side failed to recognize the Monterey side as a start up disk. The solution? Shut down the computer, [5 minutes], use the option key. If the computer is powered all the way down, option key works and displays all possible startup disks. Select the one desired. Select it in system preferences [ it will show ]. The issue is that with Mojave, only HDD Mojave or SSD Mojave show up. All Systems [Mojave on hard disk and SSD and Monterey on SSD] have been restored by download from apple. All disks pass first aid when run thru disk utilities.

If this hasn't come up then it's only my issue. If it has come up I thought there would be a larger discussion.

The powerdown work around gets me where I need to go.

-wes

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Answer 2

Owl-53

Level 10

104,863 points

Jun 4, 2022 7:23 AM in response to Wesley B. Argo, Jr.

Not side stepping the original question but does open another question related to this computer setup.

There are reports appearing on the ASC Forums regarding failed installation of Monterey on older Qualifying Apple Computers. In most cases this is related to having a NON Apple Original Internal Drive ?

In this specific computer setup the External Drive would be the Destination of this Monterey Installation.

The EFI Boot ROM included in Monterey is verifying for Original Apple Drive and if not found , may Balk or fail to upgrade to Monterey.

Reports indicate the EFI BOOT ROM is Required to Flash the Computer and is a requirement for a Successful Monterey Installation.

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Answer 3

Owl-53

Level 10

104,863 points

Jun 6, 2022 9:51 AM in response to Wesley B. Argo, Jr.

AFAIK - Monterey will not install to an Internal Drive that is not an Apple Original Drive.

That said, the Monterey will install to an External Drive ONLY once the EFI BOOT ROM has been Flashed to the computer and running Monterey.

Further, unanswered, is the specific method to have installed Monterey to the External Drive without the EFI BOOT ROM first being apple to said Computer.

Yes, there are some, how to put it, Technically Illegal Methods but would not think this was done to achieve this due boot from External Drive.

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startup disk recognition

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