If I create an external drive with Yosemite that I can boot from, will I also be able to boot from my internal drive still?

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If I create an external drive with Yosemite that I can boot from, will I also be able to boot from my internal drive still?

So I am still on Mountain Lion and I haven't upgraded because I have always been worried that Logic Pro, my Plug ins, and my Hardware wouldn't work right on the new OSX. I am now becoming interested in upgrading since Logic has a new update that I cant use.

My plan is to install Yosemite on an external drive that has thunderbolt connection so that I can boot from that and give everything a trial run. Is this something that actually works? If I do this, and things arent compatible on Yosemite, will I be able to boot from my internal and be back on Mountain Lion as I am now?

Thanks!

iMac, Mac OS X (10.7.3)

Posted on Mar 28, 2015 12:50 PM

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Answer 1

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DontKnowItAll

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Mar 28, 2015 12:54 PM in response to TheBeef

Yes. You can chose the startup disk in settings once you've got the drive up and running.

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Answer 2

Kappy

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361,741 points

Mar 28, 2015 12:54 PM in response to TheBeef

Yes, but not at the same time.

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Answer 3

Kappy

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361,741 points

Mar 28, 2015 12:55 PM in response to TheBeef

External drive must be partitioned and formatted for Mac OS Extended, Journaled.

Clone Yosemite, Mavericks, Lion/Mountain Lion using Restore Option of Disk Utility

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

1. Select Disk Utility from the main menu then press the Continue

button.

2. Select the destination volume from the left side list.

3. Click on the Restore tab in the DU main window.

4. Select the destination volume from the left side list and drag it

to the Destination entry field.

5. Select the source volume from the left side list and drag it to

the Source entry field.

6. Double-check you got it right, then click on the Restore button.

Destination means the external drive. Source means the internal startup drive.

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Answer 4

TheBeef Author

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Mar 28, 2015 1:32 PM in response to Kappy

Excellent, thank you for your help!

I am not the greatest with these things, so to make sure I understand corrently, these instructions are how to go back to my internal drive and old OS when I am ready to?

If that is the case, what are the proper steps for installing Yosemite onto the external drive instead of internal?

Thanks again!

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Answer 5

Kappy

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361,741 points

Mar 28, 2015 1:40 PM in response to TheBeef

No. They are instructions on how to clone your existing system from the internal drive to the external drive. In order to pick which one to use:

Boot Using OPTION key:

1. Restart the computer.

2. Immediately after the chime press and hold down the

"OPTION" key.

3. Release the key when the boot manager appears.

4. Select the desired disk icon from which you want to boot.

5. Click on the arrow button below the icon.

If you want to switch to a different boot drive permanently, then reset the default startup drive from the Startup Disk preference panel in System Preferences.

Of course, you would not clone your existing system if you wish to install a different version of OS X on the external drive. In that case you would need the installer for that OS X version.

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Answer 6

TheBeef Author

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Mar 28, 2015 2:06 PM in response to Kappy

Ah, okay. That makes a lot more sense.

So since I am simply installing Yosemite on the external to test it while keeping my Mountain Lion on my internal, there is no need to clone anything?

What is the best way to get Yosemite installed on my external? When I'm in the installer, will it just give me an option of which drive I want to install it on?

And when I do eventually boot up into Yosemite from the external, it will be as if it is a brand new system, right? None of my files and apps from my current OS will be there?

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