OSX on external SSD (moving to a different Mac)

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Hello there.

End of 2014 I bought a external SSD drive to use this as my Systemdrive (via thunderbolt). I installed OSX successful and worked happy the last 12 month on my iMac mid2011.

Today I bought me a brand new iMac 5k, but if I want to boot OSX from my external Thunderbolt-SSD I just see nothing as a black screen and a white sign meaning "not allowed".



On an Apple-Page I read this means that the iMac couldn't find a valid system folder.

So what happend here and is it possible to make my external OSX run on my new iMac?

A year ago I thought I'm smart because of the idea I could work on every Mac simply plugin my Thunderbold-SSD-Drive... xD

Hope for helpful hints. :)
 

keysofanxiety

macrumors G3
Nov 23, 2011
9,467
24,215
Hello there.

End of 2014 I bought a external SSD drive to use this as my Systemdrive (via thunderbolt). I installed OSX successful and worked happy the last 12 month on my iMac mid2011.

Today I bought me a brand new iMac 5k, but if I want to boot OSX from my external Thunderbolt-SSD I just see nothing as a black screen and a white sign meaning "not allowed".



On an Apple-Page I read this means that the iMac couldn't find a valid system folder.

So what happend here and is it possible to make my external OSX run on my new iMac?

A year ago I thought I'm smart because of the idea I could work on every Mac simply plugin my Thunderbold-SSD-Drive... xD

Hope for helpful hints. :)
It's likely that it's the wrong OS version, because your iMac 5K's firmware will only support the latest OS as a minimum. So if you plug it back into your old Mac and ensure it's on the latest version of El Cap, this should resolve the issue.
 
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fa8362

macrumors 65816
Jul 7, 2008
1,340
54
It's likely that it's the wrong OS version, because your iMac 5K's firmware will only support the latest OS as a minimum. So if you plug it back into your old Mac and ensure it's on the latest version of El Cap, this should resolve the issue.
Keysofanxiety is correct. You cannot use an OS version earlier than that shipped with your iMac. So if it shipped with El Capitan, you can't use Yosemite, Mavericks, or earlier versions.
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Great hint! ;) The OSX on the SSD (10.11.1) is NEWER than on the brandnew iMac (10.11)! So I will try to update OSX on the iMac and than booting from the SSD. Hoping that is the solution. :D
 

fa8362

macrumors 65816
Jul 7, 2008
1,340
54
Great hint! ;) The OSX on the SSD (10.11.1) is NEWER than on the brandnew iMac (10.11)! So I will try to update OSX on the iMac and than booting from the SSD. Hoping that is the solution. :D
If that's the case, it should boot from the external. You had finished setup on the new iMac before trying to boot from the external, correct?
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Yes, I finished the setup on my new iMac. Is this a Problem?
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Hmmm. Well, I try to update OSX on my iMac and see what happens. o_O
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Ok. Updating the OSX on the iMac does NOT helped. I still see the "not allowed" symbol. :(
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
BTW It was no problem to migrate the Data from the SSD to the new iMac.
 

cbrand493

macrumors 6502
May 19, 2015
335
223
Perth, Australia
BTW It was no problem to migrate the Data from the SSD to the new iMac.
Doesn't the new retinas use some form of custom driver that's not unanimous to all the OSX installs? So if that driver is missing (which it will be coming from an older iMac), it won't boot. Can't remember if it was something to do with the processors or the GPU/display.
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Thanks. Can't find something with Google. If someone has a more detailed hint? Would like to know more before I install OSX new on my SSD. :D
 

Weaselboy

Moderator
Staff member
Jan 23, 2005
29,132
8,805
California
Thanks. Can't find something with Google. If someone has a more detailed hint? Would like to know more before I install OSX new on my SSD. :D
This is odd. Others are correct that sometimes a new Mac will have a special OS build with specific drivers, but usually that build is deprecated when the next point release comes out.

So you might have the following:

El Capitan 10.11.0 (build 10) on existing Macs.
El Capitan 10.11.0 (build 12) on a new iMac like yours
El Capitan 10.11.1 (build whatever) that rolls in the drivers from build 12 above so now the OS is the same on all systems old and new.

Usually that special build only exists for a brief window from the time the new Mac is released until the first point release. 10.11.1 in this case.

Boot to the new iMac then also the SSD on the old Mac and look in this section of System Prefs for the build number (15B42 in my shot) and tell us what they both are.

Screen_Shot_2015-10-29_at_8_56_33_AM.png
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Thanks for helping Weaselboy :D

On the iMac 27"5k: OS X 10.11.1 (15B42), Darwin 15.0.0
On the iMac 21,5" mid2011 booted from SSD-Thunderbolt: OS X 10.11 (15A284), Darwin 15.0.0

I am confused :confused: I was pretty sure to have the newest El Capitan on my SSD.

If I update OSX on my SSD will it work then? Or maybe not because of different drivers for the older iMac?
 

Weaselboy

Moderator
Staff member
Jan 23, 2005
29,132
8,805
California
Thanks for helping Weaselboy :D

On the iMac 27"5k: OS X 10.11.1 (15B42), Darwin 15.0.0
On the iMac 21,5" mid2011 booted from SSD-Thunderbolt: OS X 10.11 (15A284), Darwin 15.0.0

If I update OSX on my SSD will it work then? Or maybe not because of different drivers for the older iMac?
Yeah... that's the issue. If you update to 10.11.1 on the old iMac (SSD) that will bring it up to 15B42 and should include the new drivers needed for the 5K and fix you up.

This is why your thread caught my attention, because usually the first point release addresses this driver issue.

I am confused :confused: I was pretty sure to have the newest El Capitan on my SSD.
Not so much. :p:D
 

Kaimling

macrumors newbie
Original poster
Oct 29, 2015
15
2
Till then I am sure I'll not have my iMac21,5" anymore. ;) So I think I have to make a new OSX install on my SSD. :rolleyes:

If that worked I'll post it here so we can close this thread. ;)
 

gallico916

macrumors newbie
Jun 27, 2014
24
7
Austin, TX
Hello Kaimling,

Sometimes when Apple issued a new machine, it ships it with a build that is dedicated to this machine regarding libraries and drivers.

If you want the best system to boot your iMac here what you should do:

  • Boot to the recovery partition on your iMac 5K (CMD+R)
  • Open the Disk Utility
  • Format your external drive for HFS+ (GUID map)
  • Install the a new system from the recovery partition on the external drive.
  • Boot to the external drive, and run software update
Enjoy
 

Weaselboy

Moderator
Staff member
Jan 23, 2005
29,132
8,805
California
Hello Kaimling,

Sometimes when Apple issued a new machine, it ships it with a build that is dedicated to this machine regarding libraries and drivers.

If you want the best system to boot your iMac here what you should do:

  • Boot to the recovery partition on your iMac 5K (CMD+R)
  • Open the Disk Utility
  • Format your external drive for HFS+ (GUID map)
  • Install the a new system from the recovery partition on the external drive.
  • Boot to the external drive, and run software update
Enjoy
That should work, but he should not have to do that since we are already on 10.11.1 that already has the new drivers. The issue is for some reason his old iMac is not picking up the software update to get to 10.11.1 that would solve this.
 

gallico916

macrumors newbie
Jun 27, 2014
24
7
Austin, TX
Weaselboy, You are right and it SHOULD work, but the way the apple OSX installer works, is that based on the current system you are running it will pull the correct libraries and drivers.
So by running the installer from the new iMac onto the external drive will guarantee the correct libraries.

Another option is to verify that his SSD is formatted using the GUID map and not the MasterBoot Recort.

A rule of thumb, is always created an image/Install on the latest hardware you have. Eventually this image/ Boot drive will be able to boot to any machine.

Regards