Can I have two instances of OSX on a Mac Pro on two separate hard drives?

You can install different versions of OS X or multiple copies of the same version, but they must each be installed either on separate partitions of the same drive or on separate drives. You can then boot whichever instance you want. To make a permanent change to the desired startup volume use the Startup Disk preferences. If you want to boot a different instance temporarily then use OPTION booting (after the startup chime press and hold down the OPTION key until the boot manager appears. Select the icon for the desired volume and click on the downward pointing arrow button.)

Hi UCLAMacConvert;

You stated; "They also are always behind in updating Pro Tools to the latest OSX support, so the second HD I would not update the OS until PT was updated to support the latest rev."

Macs are only able to boot from the OS they shipped with or a newer version. So your plan will not work because the Mac you buy next spring will only be able to run that version of OS X that is ships with and not any of the older versions that might be needed to support Pro Tools.

Allan

Allan Eckert wrote:

Macs are only able to boot from the OS they shipped with or a newer version.>

Are you positive about that ?
There are, and have been , identical Macs which have been shipping with different OS versions, namely Leopard / Snow right now.
I assume one can install Leo on any Mac coming with Snow, no ?

If a newer system is installed already, you'll need to wipe the system harddrive first to get the older OS on it, of course.

Hi thanon;

No. If it shipped with Snow Leopard installed it will not run Leopard.

It has been Apple's policy that a Mac will not run an older version of the OS.

You can do anything you want but it don't work no matter what you do.

Allan


Message was edited by: Allan Eckert

Hi UCLAMacConvert;

I don't know enough about all the internals to give an absolute answer to your question.

What I am quoting is the policy as stated by Apple which is if it shipped with 10.6.2, even if we believe the hardware is still the exactly the same, it will not run anything earlier then 10.6.2. That is what they say.

If you need further clarification on that you will have to take it up with them.

Allan


Message was edited by: Allan Eckert

Allan Eckert wrote:
Hi thanon;

No. If it shipped with Snow Leopard installed it will not run Leopard.

Thanks for clarifying; that's weird , though.

While that is often true, it is probably inaccurate also, and could be more accurate to say "may not boot."

There hasn't been any difference in hardware since then, and maybe not SMC or EFI firmware as well.

Just because it shipped with 10.6 doesn't mean it won't run 10.5.8. It may install 10.5.7 or later only however. Biggest issue is often lack of driver support for graphic cards. Which is lame.

Agreed; a little research suggests that there is a thing called 'minimum' and 'maximum' OSX working for any given Mac, -->

http://www.apple-history.com/

10.5.6+ seems to be working still for any recent Mac; I'll find out soon when I get a MB for my parents and try to install Leopard.
I assume the combo updates cover any driver and kernel needs there might be, if the install works in the first place.

Hi thanon;

The OP stated he was getting a Mac Pro when the new model is released so all of this talk about no hardware changes and being able to run 10.5.6+ is of no consequence to him. He will have new hardware and as in the past this new hardware will probably be released with its own version of Snow Leopard that it will have to use and nothing older then that version.

Allan


Message was edited by: Allan Eckert

Allan Eckert wrote:

The OP stated he was getting a Mac Pro when the new model is released so all of this talk about no hardware changes and being able to run 10.5.6+ is of no consequence to him.

Hi Allen,
That's certainly right, upcoming models might not be backwards compatible to 10.5.x - which is something to be considered before buying, I guess.

To quote the hatter, it'd be pretty lame to not have the option for a professional desktop machine, though.

Hi thanon;

It may be your opinion that it is lame but that has been Apple's policy all along. The reason I heard stated for this policy is because of the tight integration between the hardware and software. Personally I don't see it as a problem.

Allan

I just got 2 Mac Pros about 2 weeks ago with Snow Leopard pre installed, (sorry didn't see if it was 10.6.2). Simply placed my old drives 10.5.8 into the drive bays and booted from them with no problems at all.

So what this 'integration' says is that if you change something as small and simple as the front side bus, or instead of Xeon 51/5300 for a 5400 Harpertown, you need a totally new OS?

2003 around this time: I saw 10.3.0 literally rushed out the door (or down the rabbit hole), but the G5 with 10.2.7 was in dire straights even if 10.3.2 would be better or best but not ready for another 2-3 months (10.2.7 was a special build at that, never public - which got 10.2.6 and then 10.2.8). Totally understandable.

Jump forward to 2008 saw a "confluence": THREE NEW ITEMS: New OS + new Mac Pro model; and 10.5. Adobe was having to push CS4 out the door. 10.5.0/.1 was new, unstable, and very very different. Luckily 10.5.2, the minimum OS for "Early 2008" wasn't as bad as all that, (10.4.12 I guess was too high?).

And now 10.6 is just "cleaning up, nothing new" though 64-bit clean and of course, once again, all new drivers and more were needed, and broke, and us with our pcie cards left hanging...

Anything, taken to extremes, can have unintended consequences.

Graphic publishing houses are often not on bleeding and cutting edge, heck, sometimes they have been happy to stay with an OS (like OS 9 for Mac) beyond its true usefulness, as perceived by others.