Problems installing macOS on external Thunderbolt SSD

[Killerbob]

Hi,

I need to test something out on my Mac Pro Trashcan. I have a Samsung EVO SSD in a thunderbolt case from Lacie, and I started the Big Sur 11.2.3 installation process using the external SSD as the installation disk. But when the Mac Pro restarts as part of the process, the boot manager does not see the SSD. It sees my internal SSD and the Bootcamp partition, but not the external SSD drive.

I reformatted, using both APFS and Mac OS Extended (Journaled) as the Format, and both times GUID Partition Map as the Scheme. But it doesn't work...

Any suggestions?

 

[Killerbob]

I thought about one thing...

Is this all because the buspowered Lacie drive is not properly up and running at Boot? And I need to use USB3 SSD instead?

 

[joevt]

Can your nMP see the Thunderbolt drive if you boot into Startup Manager (hold the Option key at boot) and then connect the Thunderbolt drive?

 

[Killerbob]

Nope, the Thunderbolt SSD does not show up in Startup Manager. When I use the USB3 connection it shows up and I can boot using the SSD, but not via Thunderbolt.

 

[joevt]

Looks like the nMP can't boot from Thunderbolt but it's hard to prove a negative. I don't recall Macs ever not being able to boot from Thunderbolt.

Which Samsung EVO and LaCie case are you using?

Do you have different SSDs and enclosures to test?

Do you have another Thunderbolt 2 or Thunderbolt 3 device to connect the bus powered enclosure to?

 

[Killerbob]

The Lacie SSD is the 500GB Rugged USB3/Thunderbolt, and the SSD is a Samsung SSD 940 EVO.

When I tried to boot off the SSD via Thunderbolt, the only other Thunderbolt devices were my ATDs, and I unfortunately do not have any other Thunderbolt SSDs to test with. Like I said, it works via USB3, but not Thunderbolt. Once into macOS, I can connect and use my other Thunderbolt devices just fine - I also have the 4TB Rugged USB3/Thunderbolt HDDs for backup.

 

[joevt]

The Rugged USB3/Thunderbolt enclosure that I could find is only Thunderbolt 1 (10 Gbps). I didn't see a Thunderbolt 2 version.
I can't find info on the Samsung SSD 940 EVO.

Did you try connecting the Thunderbolt enclosure to the ATD display?

 

[Killerbob]

OK, I probably remember wrongly then, and the SSD is a Samsung 850 EVO 500gb SSD.

Does it make a difference if the Lacie is Thunderbolt 1 or 2? I am not trying to do this for speed, I just want to use the SSD for booting to test something out...

 

[joevt]

Does it make a difference if the Lacie is Thunderbolt 1 or 2? I am not trying to do this for speed, I just want to use the SSD for booting to test something out...

I'm not sure. There's a lot of variables but you don't have the options to test them.

Did you try connecting the Thunderbolt enclosure to the ATD display? That's one variable you can test.

 

[Killerbob]

I did actually, and it still does not show in the Boot Manager. Anyways, thx for your suggestions. I'll just have to stick with USB3 for now, which is OK, as it is just for testing. I'd never boot of an external drive regularly anyway...