Login using an ext drive

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Level 1

4 points

Login using an ext drive

My hd is failing so have loaded catalina on ext drive. I hold down option key to open on ext drive but takes 2-5 DAYS to get to login screen. What is a Better way?

iMac 21.5″, macOS 10.15

Posted on Nov 14, 2021 10:39 AM

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Answer 1

Top-ranking reply

jeffreythefrog

Level 6

12,614 points

Nov 14, 2021 10:57 AM in response to Nhojway

you can try going into SystemPreferences > Startup Disk and set the external drive to boot from.

i'm thinking if it's slow to load using the option key on startup, that may be due to the failing internal drive. but frankly, that's just a guess. :)

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Answer 2

ku4hx

Level 7

23,586 points

Nov 17, 2021 5:48 AM in response to Nhojway

Are you by chance using a spinning platter external drive to boot from? If you are, that's going to be really slow. The fix in this case is to use an external SSD.

Seagate backup plus slim 2TB:

120 MBps (as shown on Amazon) is not going to be fast enough to be a practical external drive. I've got a pair of cheap PNY SSDs that work very well for external booting. The 250GB versions were about $40US when I got them; their read speeds are in the 440 MBps range.

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Answer 3

Nhojway Author

Level 1

4 points

Nov 16, 2021 9:02 PM in response to Jack-19

Yes it takes 1-5 days or usually 2 -3.

It is old but works fine after it manages to load. Late 2012 running updated Catalina installed on an external HD

Seagate backup plus slim 2TB. Catalina is the last version it will accept.

Every update usually requires a restart. I hold the Option key down for

60-120 seconds immediately after the startup sound is heard. I can hear the Seagate start and run. Usually, it stops while the Option key is still depressed. Cannot figure out the exact pattern to follow. It runs white for a while, maybe Apple shows and starts loading, then goes black or grey (showing only modem and country in the top right-hand corner), maybe comes back to Apple, says it will be 28 more minutes, etc etc. It eventually shows up with the login screen.

It may take longer than usual partly because it starts on an external HD, plugged into a (non-thunderbolt) USB slow-speed, and because I have the worst internet speed of only 10Mbs. If I can ever get better internet speed, I will buy a new iMac. I may do that anyway.

Some have suggested going to Preferences and set Startup disk to external HD. I am familiar with that, but do I click "Target Disk Mode" thereby setting it to always use ext HD to start? That was not clear to me.

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