Don't think I have it in me to help friend with 2015 iMac 21.5" swap HDD to SSD

[jdc]

GGD wrote:
Unless things have changed radically over the years, you should be able to use the Startup Disk system preference to select the external boot drive, and as long as it's powered on, it should boot from it on restarts and power ons.

Exactly. Its always powered on, since its a bus powered drive. =)

Choosing the correct drive at startup requires no more than holding down the option key at startup and choosing the correct drive.

[GGD]

jdc wrote:
[quote=GGD]
Unless things have changed radically over the years, you should be able to use the Startup Disk system preference to select the external boot drive, and as long as it's powered on, it should boot from it on restarts and power ons.

Exactly. Its always powered on, since its a bus powered drive. =)

Choosing the correct drive at startup requires no more than holding down the option key at startup and choosing the correct drive.
I'm confused by your answers and experience.

You answered "Nope" to can it automatically select the drive, and "Exactly" to my description of how Startup Disk works.

So does Startup Disk work for you or not? Or do you just prefer using the option key.

[Robert M]

GGD,

JDC's answers are a bit confusing. In my experience, Startup Disk works and using it to determine the boot drive is preferable. That way, the machine knows which drive is the preferred boot drive and automatically boots off it when possible. If it can't find that drive, it'll start looking for alternates to the chosen drive.

The only time I use Option upon boot for drive selection is when I intentionally want to the machine to boot from alternate drive. That could be for booting off a clone of the primary boot drive, a maintenance drive for performing maintenance on the primary drive, booting off a drive with a newer flavor of the OS for testing purposes, etc. There is no need to hold option upon boot to choose a boot drive under normal circumstances.

Robert

[Robert M]

pRICE,

Definitely switch him to an external boot drive. Easiest thing to do is buy a USB-C drive and connect it to one of the USB 3.0 ports. Might need a USB-C to USB 3.0 cable or adapter. Doesn't matter. Don't try to connect the drive to the Thunderbolt 2 ports of the machine. Won't work.

Once the external connected, clone the boot drive to it with Carbon Copy Cloner. Reboot, holding option to allow you to choose the external as the boot drive. Once it's booting off the external and working nicely, choose the external as the boot drive in Startup Disk. Done. Once you do that, it will always try to boot off the external first and should be seamless to your friend.

There will be a tangible improvement even if using an external SSD connected via USB 3.0. But, given the choice, don't go with a 2.5" based external with a USB 3.0 connection. Go for a faster model with a USB 3.1 Gen 2 connection. Offers a bit of future proofing. If he moves to a desktop with a Thunderbolt 3 or 4 port, you can move the external to it and still enjoy a speedy boot drive.

Robert

[jdc]

GGD wrote:
So does Startup Disk work for you or not? Or do you just prefer using the option key.

You right, I should have been more specific.

IF there were ever an issue with the startup drive not being the startup drive... holding down the option key allows you to choose whichever drive you want as the startup.

I wasn't trying to get too detailed, since the odds of it happening are incredibly small.

Curretnly, Ive been booting from an external for 4 years, I cant remember ever having to use the option key option? (I mean maybe, but my memory isn't that good, and I rarely, restart. like months and months)