Mac with multiple boot drives

[netnothing]

Currently I have a Mac Pro with the stock 250GB in bay 1 and a 500 GB drive in bay 2.

When Leopard gets released, If I go out and get another internal 500GB drive, and I want to do a clean install of Leopard on that drive:

1) Can I have both this new drive and the current Tiger boot drive in the machine at the same time?

2) How does OS X know which to choose at boot?

3) Can I use the Migration assistant to point to the current boot drive still in the machine to migrate over user data once I get Leopard installed on the new drive?

Basically, I want to be able to get Leopard on Day 1.....and install it. But want a easy way of rolling back if apps don't work right for me. And I'd like to do a fresh clean install of Leopard anyway, and copy settings over from the other drive.

I guess, is the Mac smart enough to pick the newest OS installed on a drive and not worry about the other in the machine, and let me access it as a secondary drive?

In the end, I'd really like to use the current 250 GB drive as a clone-only backup solution.

I'd be using my 500GB OWC external for all Time Machine backups.

Thanks!

-Kevin

 

[Not-a-cliche]

I'm not sure what will happen right after you install Leopard, but I think it will probably boot to Leopard.

Then, to get back to Tiger, you hold Option during boot.

If for wacky purposes it boots to Tiger instead just go into System Prefs and change the selection in the "Startup Disk" section.

It's entirely possible to do this.

 

[netnothing]

So....3 questions:

1) I'm assuming you can have more than 1 bootable drive with an OS installed in a Mac? The one that starts is tied to whatever preference is set in Sys Prefs? So technically I could have 2 drive with Tiger on it and switch back and forth?

2) Do you have to do something when you partition or format to make the drive bootable? or is that done when the OS gets installed?

3) So technically, when you set the startup drive is System Preferences....does that write something out to EFI on the motherboard to tell the machine which drive to boot to?

-Kevin

 

[mkrishnan]

1) I'm assuming you can have more than 1 bootable drive with an OS installed in a Mac? The one that starts is tied to whatever preference is set in Sys Prefs? So technically I could have 2 drive with Tiger on it and switch back and forth?

Yes, my backup drive has multiple bootable partitions on it.

2) Do you have to do something when you partition or format to make the drive bootable? or is that done when the OS gets installed?

The drive has to have a bootable partition scheme (Apple or GUID), and the partition has to be of a format that is conducive to booting the OS in question (e.g. the OS X partition should probably be HFS+). Otherwise, no, when the OS is installed.

3) So technically, when you set the startup drive is System Preferences....does that write something out to EFI on the motherboard to tell the machine which drive to boot to?

I think so, but I'm not sure.

 

[netnothing]

Yes, my backup drive has multiple bootable partitions on it.



The drive has to have a bootable partition scheme (Apple or GUID), and the partition has to be of a format that is conducive to booting the OS in question (e.g. the OS X partition should probably be HFS+). Otherwise, no, when the OS is installed.



I think so, but I'm not sure.

Thanks for the quick reply. I did format the drive Mac OS Extended (Journaled) and with the GUID Partition Table. So once an OS gets installed on that drive, OS X will see that it can boot to it, and add that drive to the Startup Sys Prefs?

I'm just guessing that it must write something to a chip on the Motherboard for the startup preference because switching back and forth between OSes would just result in that OSes prefs.

-Kevin

 

[mkrishnan]

Yeah, I can check mine again when I get home, but you should see an entry for every bootable partition available. E.g. when you put in a system restore DVD, it shows up in the startup disk list. You should see each bootable partition on each hard drive that is connected to an interface that is capable of being booted from, if that makes sense.