Base level 2018 Mini - 128GB SSD and 8GB RAM. Upgraded to Catalina and seemed OK for a while. I have a LaCie connected by a TB3 to TB2 adaptor and set up as Mirror RAID, one partition of which holds a SuperDuper clone which is working fine. Switching on the Mini one day and it was taking ages to boot with a lot of disk activity on the LaCie. It was booting from the clone and not the SSD. I let it finish booting and checked which startup disk was enabled. It was the correct disk. Restarted and it booted correctly and did so for the next few days. Then it did it again. So far it has booted from the clone 3 times at random intervals. I could always startup with the Option key but this is not ideal. Or I could disconnect the LaCie and reconnect after booting. This also is not ideal. Any ideas anyone?

On 31 Oct 2019, at 15:31, Jim Saklad via Groups.Io <jimdoc@...> wrote:

On Oct 31, 2019, Joe Masters wrote:

Base level 2018 Mini - 128GB SSD and 8GB RAM. Upgraded to Catalina and seemed OK for a while. I have a LaCie connected by a TB3 to TB2 adaptor and set up as Mirror RAID, one partition of which holds a SuperDuper clone which is working fine. Switching on the Mini one day and it was taking ages to boot with a lot of disk activity on the LaCie. It was booting from the clone and not the SSD. I let it finish booting and checked which startup disk was enabled. It was the correct disk. Restarted and it booted correctly and did so for the next few days. Then it did it again. So far it has booted from the clone 3 times at random intervals. I could always startup with the Option key but this is not ideal. Or I could disconnect the LaCie and reconnect after booting. This also is not ideal. Any ideas anyone?

Is the SSD extremely full?

It sounds to me as though there is some problem with the internal boot drive, perhaps sometimes slowing down whether or how quickly it is recognized by the system.

I would shut down, unplug all external drives, and boot into Recovery Drive (Press and hold Command-R until the progress bar appears).

In Recovery mode, go to the menu and run Disk Utility

Run First Aid on your boot volume.

You should then be able to shut down, connect the external, and run normally.