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Any experience out there with installing multiple separate Mac os x bootable installs on a single partitioned drive (owning multiple licenses, naturally)? This would be done in order to allow for one reliable stock OS and a second install for tinkering with kernel internals, without having to circumvent Apple's prohibition on virtualizing os x.

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up vote 1 down vote accepted

My primary computer is set up this way. At the moment I'm using 10.6 as my main OS, and I also have a 10.5 partition for compatibility testing. I've used it in the past to install seed builds, etc. without disturbing my regular system. Works fine, no need for rEFIt or anything fancy. You can switch systems either with the Startup Disk preference pane, or simply by holding Option when booting (which invokes the startup manager built into the firmware).

Sharing files between the OSes is a little tricky unless you're careful to keep the UIDs consistent between the systems (e.g. I'm user #501 on both/all systems, so all my accounts can access each others' files).

To set up for this, either run Disk Utility from the utilities menu on the install DVD, or if you already have the OS installed you can run Disk Utility from the live system. You can shrink the existing partition if needed to make room for new partitions, but note that you can't move (i.e. you can change where each partition ends on disk, but not where it starts), so your ability to shuffle partitions to make room is a bit limited. Also, if a partition is too fragmented, it may not be shrinkable -- the time I ran into this, I ran iDefrag to solve it.

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Have a look at rEFIt. I personally use it to triple-boot OS X, Kubuntu and Windows XP on my Macbook. It works very well.

rEFIt is a boot menu and maintenance toolkit for EFI-based machines like the Intel Macs. You can use it to boot multiple operating systems easily, including triple-boot setups with Boot Camp. It also provides an easy way to enter and explore the EFI pre-boot environment.

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Gordon is right of course, no need for rEFIt if you only run multiple OS X versions. – Martijn Heemels Sep 12 '10 at 16:06

When you boot to the CD, you can select the partition or disk on which to install the OS. I don't have a machine at hand to tell you the exact step you have to select it, but I'm pretty sure that you don't need to hit a "Customize" button or the like to get to this option.

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If you run VirtualBox on Mac hardware, it is possible to install a virtual machine running the client versions of OS X. This has quickly become an extremely valuable tool for me because it made testing so much easier.

N.b. it might be possible that Oracle pulled that feature later on, the docs are a bit inconsistent about that, but it's free, so just try it.

Other than that, back in PPC days, multiboot from different partitions worked flawless. If you experience problems, you can still connect an external HD via the FW800 port and work from there. It's a bit slower, but acceptable for experimental work.

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It is against Apple's licensing to run OSX Client virtualized. You may, however run OSX Server as a VM, as long as the underlying hardware is Apple. – gWaldo Sep 9 '10 at 12:50

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