Able to boot from external ssd, but ssd doesn't appear in startup disk menu

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Able to boot from external ssd, but ssd doesn't appear in startup disk menu

Hi, Just got a new old stock 2017 iMac 21.5 - 3GHz Core i5, 8gb RAM and a terribly slow internal drive.

I have cloned the old ssd from my aged Macbook Pro onto a Samsung T5 portable SSD and can successfully boot the iMac upon startup by holding the option key and selecting the SSD, but when I go to the Startup Disk trying to have the iMac automatically use the SSD to boot the computer, the Samsung T5 doesn’t appear in Startup Disk.

The T5 shows up in disk utility and it sure looks like it’s mounted and I can access data from it, but I’ve not figured out how to make it the startup disk.

Anyone here have any ideas?

Thanks

Jeff

Posted on Jul 27, 2019 3:33 PM

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Answer 1

Best reply

den.thed

Level 9

77,866 points

Jul 28, 2019 1:51 PM in response to donthackthisaccount

I think that woodmeinster50 is spot on, cause the same thing happened to me a couple of times.

To fix and bless the drive as the startup disk, I had to backup the drive, startup in mac OS Recovery, use Disk Utility to erase and re-format the drive, install macOS on the drive, then startup and Migrate from backup during the setup.

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Answer 2

HWTech

Level 9

56,318 points

Jul 27, 2019 6:34 PM in response to donthackthisaccount

I like to use Carbon Copy Cloner to clone bootable volumes and never had a problem on compatible systems. I don't know what you used, but I've had issues in the past when using Disk Utility to clone a bootable drive.

Try an SMC reset and PRAM reset (hold the PRAM reset for a full minute so it activates several times).

You can try using the "bless" command which is now deprecated, but may still work. The currently recommended way of configuring the startup disk using the Terminal command line is using the "systemsetup -setstartupdisk" command. While I have "used" both of these commands, I really don't know/recall the proper way to use them for a macOS volume.

Another option is to use the rEFInd boot manager or to perform a clean install and migration.

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Answer 3

Jul 28, 2019 3:52 AM in response to donthackthisaccount

The issue could be you are trying to boot with a clone from a completely

different Mac. What you need to do is try to clone the iMac's drive to the SSD.

While the "Option" boot may work, the normal select "boot Drive" may not

recognize it as "belonging" to the iMac.

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Answer 4

Jul 28, 2019 1:21 PM in response to HWTech

HWTech, Thanks for replying back and for your help!

I used SuperDuper to clone the drive from the MBP. Figured it would be a good solution, but I'm guessing there are issues beyond the SuperDuper cloning tool.

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Answer 5

Jul 28, 2019 1:23 PM in response to woodmeister50

Hi Woodmeister50, Thanks for your reply and for the assist.

Let me ask 1 final question on this.... Do you think I would encounter any issues with continuing to simply select the external SSD as the boot drive in perpetuity? If not, I may just run with this small annoyance and be happy to have a newer, much quicker machine than my 2011 MBP I migrated from.

Thanks again!

Jeff

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Able to boot from external ssd, but ssd doesn't appear in startup disk menu

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