Run 2 different OSX on 2 partitions of the same HD

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Level 1

8 points

Run 2 different OSX on 2 partitions of the same HD

Hi there. I purchased an iMac 27" running Mountain Lion (OS 1O.8.5).

In order to keep using older software, I need to keep this OS version.

However, I partitioned my HD to be able to run the latest OS on the new HD partition.

I understand that I cannot install directly the latest OS Sierra on my new partition but have to go through El Capitan first. Is that correct? I tried to get it from the Apple store but it says my computer doesn't meet the requirements.

Do I need to purchase Mountain Lion from the Apple store, install it on the new partition, then upgrade to El Capitan and finally to Sierra?

The desired outcome is to be able to boot from either one of the 2 partitions and use one OS or the other.

What is the best way to proceed?

Many thanks.

iMac (27-inch, Late 2012), OS X Mountain Lion (10.8.5)

Posted on Dec 14, 2017 3:21 PM

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Answer 1

Best reply

Kappy

Level 10

361,741 points

Dec 14, 2017 3:45 PM in response to WildYann

Keep in mind you cannot run more than one OS concurrently unless you use virtualization software.

Run Windows on Intel Macs

There are presently several alternatives for running Windows on Intel Macs. Here is a list of the primary options in the marketplace.

Apple Boot Camp software. Boot Camp enables you to boot the computer into OS X or Windows. (Free because it comes with OS X. You must own a legitimate Windows Full Retail Installer.)
Parallels Desktop for Mac. Parallels is software virtualization that enables running Windows concurrently with OS X.
VM Fusion.VM Fusion is software virtualization that enables running Windows concurrently with OS X.
CrossOver. Enables running many Windows applications without having to install Windows. The Windows applications can run concurrently with OS X.
VirtualBox. Open Source freeware virtual machine such as VM Fusion and Parallels that was developed by Solaris. (Free because it comes with OS X. You must own a legitimate Windows Full Retail Installer.)
Veertu. A new entry from Open Source utilizing native virtualization. It’s a fast and secure way to run VMs on the Mac. Veertu Desktop is supported on Mac models of early/mid-2011 or later running Yosemite 10.10 or later.

Parallels, VM Fusion, VirtualBox, and Veertu can also run other operating systems such as Linux, Unix, OS/2, Solaris, etc. There are performance differences between dual-boot systems and virtualization. The latter tend to be a little slower (not much) and do not provide the video performance of the dual-boot system. A 2015 comparison of Parallels, VM Fusion, and Virtual Box is found at 2015 VM Benchmarks: Parallels 11 vs. Fusion 8 vs. VirtualBox 5. A review of these and other competitors is found in PCMag: The Best Virtualization Software of 2017. Boot Camp is available with Lion and later.

You must also have an internal optical drive for installing Windows. Windows cannot be installed from an external optical drive. Windows must be installed on an internal drive if you use Boot Camp. A license must be purchased for all commercial software and operating system products. Open Source software is free.

Some Boot Camp Articles from Apple Support.

Boot Camp Support.

Boot Camp 5.1: Frequently Asked Questions.

How to Install Windows using Boot Camp.

Boot Camp Control Panel Users Guide.

Use Windows 10 on your Mac with Boot Camp.

Use Windows 8.1 on your Mac with Boot Camp.

Install Windows 7 and earlier on your Mac using Boot Camp.

System Requirements to Install Windows on your Mac using Boot Camp.

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Answer 2

WildYann Author

Level 1

8 points

Dec 14, 2017 3:29 PM in response to Niel

Hi Nigel. Thanks so much for your quick reply! I downloaded OS Sierra but didn't proceed to the 'set up installation' phase as I feared it would upgrade automatically the OS on my old partition (replace OS Mountain Lion). Are you saying I will have the option to install it only on the new partition?

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Answer 3

WildYann Author

Level 1

8 points

Dec 18, 2017 10:05 AM in response to Niel

Hi again. Partitioning worked great as well as installation of latest OS on new volume.

However, when I restarted the computer, I expected to see both my old profile with old OS and new profile with new OS... but it was not the case: the only options available are now the new profile and a guest profile without password required. Does it mean I accidentally overwrote the old profile and it's gone for good? Or do I have to press a key on restart to see the old profile? The interesting thing is that in the finder, the old volume is visible with all legacy applications. However, of course, they don't run on High Sierra.

Did my old profile disappear because of identical naming (the partitioned volumes have their own names however with own passwords)? Or did I need to do something to make it bootable/visible after restart?

Any additional help would be hugely appreciated.

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Answer 4

Niel

Level 10

726,689 points

Dec 19, 2017 6:23 AM in response to WildYann

You need to restart with the Option key held down or use the Startup Disk pane of System Preferences.

Installing a second OS works at a different level from creating a new account. It isn’t possible to see accounts from different OS installs at the same login screen.

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