Has anyone ever booted from an external drive? System 10X6+

All the time. Modern EFI firmware Macs can boot from anything containing a valid OS X boot volume. This means a drive in HFS (Apple Extended) format and with GUID partitioning scheme.

Press and hold Option/Alt prior to the startup chime. That invokes the interactive startup manager. A string of icons will pop up onscreen, corresponding to any and all bootable volumes visible to the Mac. Click on the desired victim, then click on the arrow underneath.

What you say makes sense. However, I am seeing something new now.

I just picked up a new MBP last week and today tried to boot from an external drive. I had been using the external drive to boot up my previous (mid-2010) MBP and it is running the latest 10.9 (and working fine on my other machine). However, when trying to boot my late-2013 from it, I am getting nowhere. Holding down Option does give me a list of volumes to choose from that includes the main volumes from the internal and external disks as well as each disk's repair volume. However, upon selecting the external drive, it brings up a grey screen with a slashed circle. FWIW, I also tried booting from it by selecting it in the Startup Disk settings with the same outcome.

When running diskutil list in the terminal, both drives have identical construction except for their names. This includes a GUID partition scheme and APPLE_HFS format.

All the newest Mac computer use a Special build of OS X, which ever version they come with, that contains the correct driver package for the new hardware in the system. It will not boot from any disk that does not contain those newer drivers for the new hardware. That is why your external from your 2010 model won't boot your new Mac.

If you make a clone of the new Mac's drive to an external it will then boot your new mac or your old Mac.

Once Apple comes out with Mavericks 10.9.1, releases it to the general public, and you install the Combo 10.9.1 update on your old Mac and make a new clone of it, or install it on that external drive from your old Mac, it should then boot your new Mac as the Combo update should contain all drivers for all Mac hardware Mavericks can run on. Including the most recently release Mac computers.

And, BTW, that's why you see the grayed screen with a slashed circle on the formerly bootable volume. Doesn't have what it takes for the new gear.

Wow! That's really messed up. I don't know why they have to make these things so difficult, especially when it's worked fine for years. It ***** in particular because it means that I can't run some apps on my new machine until this update comes out. Hopefully it will arrive soon.

Anyway, thanks for clarifying the issue. I'll just sit tight, wait, and hope they don't screw things up even more.

Not at all!

If you had uses the setup assistant system when you first turn on that new Mac you could of copied over all the Apps settings and files from that clone to the OS X install that came on the new Mac. Just because a new Mac can't boot from a clone of an old Mac doesn't mean you can use the same apps on the new Mac. You can even install them manually.

I wonder... Can you use the carburator from your Grampa's wheels on your new car? "No way!", you'll say; it's a whole different ballgame. But you can still use the stereo, the speakers (if not busted) or even the GPS, right? Maybe the core of the old vehicle (engine & its management, transmission, chassis, suspension) can't be used in a modern car, but many of the accessories can. Same thing here: the newest Macs have the latest from Intel, which is a world apart from processors 2-3 generations ago. And the Operating System that talks directly to the hardware has to follow suit.

At First Start, the Setup Assistant did give you the option to migrate your stuff from the older computer. Were it a Mac, settings, files and compatible applications could have been transferred over (in many cases, even with their registrations or activation codes). Had it been a PC, only files and compatible settings could have likewise moved over. If that wasn't taken advantage of at the time, two options remain for getting the stuff over without too much hassle:

Run Migration Assistant and use that instead. Migrating user accounts and files contained in their Home directories can be tricky if they are named the same as those already on the new Mac, but apps and non-personal files (not in duplicated Home directories) can transfer fine.

Reinstall the OS to redo the First Start.

And FYI, a new Mac from last week will ONLY run the latest Mavericks.

And FYI, a new Mac from last week will ONLY run the latest Mavericks.

Nope, I was booting ML from a clone of a year old Mac mini onto a completely new MacBook Air just a couple weeks ago

Works fine

In general I agree with you, but that blanket statement isn't accurate

PlotinusVeritas wrote:

In general I agree with you, but that blanket statement isn't accurate

Oh, sure, before the latest firmware update I even managed to boot Leopard on my Mac once but for users who may not be well versed in the intrincacies of the HW/FW/OS interactions, it is safest to stay with the OS your Mac came with.

Yup. Agreed