OK, here's my situation :
- I am a developer needing to debug under different OS X versions
- I currently own 2 macs : a MacBook Pro and an iMac
- the iMac has Snow Leopard (10.6) on it – it came pre-installed
- the MacBook has been upgraded to Lion and then to Mountain Lion (10.8)
- I have purchased Lion & Mountain Lion via the App Store.
What I need :
- Install OS X 10.7 along with some of the other installations (in a different partition? via something like Parallels? I don't know… Ideas?)
Questions :
- What's the best way I could achieve that? (I don't care if 10.7 will go with 10.6, or 10.8)
- Where can I find an installation package for 10.7? (remember, I've already bought it)
Note : I'll most likely do it using partitions. The core of the question is : WHERE is my 10.7 installation file???
Best Answer
This is entirely possible. I use either of both of the following variants depending on what I'm trying to test:
Virtual machines
You can run OS X 10.7 and newer inside recent versions of Parallels and VMWare Fusion. You can also run the server variants of older OS X versions this way; these older server variants also work on VirtualBox, which is free for personal use.
Advantages:
Disadvantages:
I don't have Parallels, but when I tried it, installation was pretty straightforward. VMWare Fusion just requires the Lion Installer.app (or Mountain Lion Installer.app) from the App Store for setting up a VM. When it asks for a disk or disk image, just drag the installer .app from Finder into the assistant window.
Multi-boot
You can install additional instances of OSX on your computers, and easily switch between them, either via Startup Disk in System Preferences or by holding the Alt/Option key when you hear the boot chime.
You can either repartition your existing disk - shrink it via Disk Utility and add an extra partition during setup - or install onto an extra hard drive or SSD. This can be an external USB or Firewire drive. Some Thunderbolt drives are also bootable.
The Installer.app
It's a good thing you've already purchased Lion, as you can no longer buy it from the App Store. The easiest will be to download it on your Mac running Snow Leopard: open the App Store, ensure you're logged in with your correct Apple ID and click the "Purchased" tab. You should be able to download Lion there.
When the download is done, it'll be an App in the Applications directory. Do not run it as that would upgrade your Snow Leopard install. If going the VM route, you can use the .app directly, otherwise you'll need to extract the InstallESD.dmg from the .app bundle and "restore" it to a USB stick (min 4GB) via Disk Utility. You can then boot from this stick by holding the Alt key when you hear the chime.
I also recommend backing up the installer app, as re-downloading it from the App Store from Mountain Lion is not possible out of the box. There are work-arounds, but I wouldn't rely on them continuing to exist.