Windows on my Air with no Mac OS, can I install Mac OS and save my windows install?

[spinedoc77]

I have Win7 RC installed on my Gen2 Macbook Air, it's installed natively, with no Mac OS on it at all. I do have bootcamp installed. It runs perfectly.

But I'd like to try out the newest Mac OS and would like to dual boot. Is there any way to install Snow Leopard but not lose my Windows install? I've got too much in it to have to redo windows.

 

[psingh01]

You'd probably have to partition your disk first so that when the Snow Leopard installer runs you pick the partition you want and it *should* just touch that. Otherwise it might just try to format your entire drive. Partition Magic used to let you partition your drives under windows without losing any data. I don't know if that software is still used today though.

 

[gr8tfly]

Even if you do an "erase and install" (I personally recommend the default upgrade install), it'll only affect the target partition (unless you accidentally choose the wrong partition).

 

[After G]

You could always boot SL from an external drive, and not touch the partition, just to try it out.

 

[spinedoc77]

Hmm so it sounds like I need to make a new partition, which is easy enough in Windows itself. So I could go into disk manager and create a new partition and install OSx onto that, sound right?

I'd like to make the smallest partition possible as I'm only trying OSx out. What is a safe size to make the partition for the 10.6 snow leopard OSx install?

Also will I have any boot problems? Or will the Apple firmware pick up the 2 OSes and give me a boot option?

 

[gr8tfly]

Hmm so it sounds like I need to make a new partition, which is easy enough in Windows itself. So I could go into disk manager and create a new partition and install OSx onto that, sound right?

I'd like to make the smallest partition possible as I'm only trying OSx out. What is a safe size to make the partition for the 10.6 snow leopard OSx install?

Also will I have any boot problems? Or will the Apple firmware pick up the 2 OSes and give me a boot option?

(You mentioned using Boot Camp: if you previously had OS-X on and used the Boot Camp Assistant to create the Windows partition - then erased the data in the OS-X partition (no modifications to that partition), then you might be able to reuse the prior OS-X partition. Otherwise, I assume you just mean using the Boot Camp drivers.)

If you have no OS-X at all, and the disk has been re-formatted using MBR partition table, you will not be able to install and boot OS-X. It requires a GUID partition.

If you have another Mac available, you could make an image of your drive using WinClone, and use that later after using OS-X's Boot Camp Assistant to restore your Win7 install. Otherwise, you might be able to use something like Ghost or other Windows imaging software. I'll have to leave it to some other reader to confirm whether that would work. WinClone has been 100% for me when moving or modifying Boot Camp partitions.

Even if Partition Magic can change the partition table to GUID without loss of data, I don't believe it will help. The way Apple did the dual boot is by simulating a MBR from within the GUID. That's what Boot Camp Assistant does when it creates the Windows partition.

To answer the size of an OS-X partition question: I have Snow Leopard installed in a 25GB partition with some tools, like Disk Warrior, for emergency and management use. SL and the basics (including Disk Warrior) took less than 11GB.

 

[spinedoc77]

Thank you for the excellent answer. I'll probably just bite the bullet and reinstall everything in a couple of months when Win7 final comes out.

(You mentioned using Boot Camp: if you previously had OS-X on and used the Boot Camp Assistant to create the Windows partition - then erased the data in the OS-X partition (no modifications to that partition), then you might be able to reuse the prior OS-X partition. Otherwise, I assume you just mean using the Boot Camp drivers.)

If you have no OS-X at all, and the disk has been re-formatted using MBR partition table, you will not be able to install and boot OS-X. It requires a GUID partition.

If you have another Mac available, you could make an image of your drive using WinClone, and use that later after using OS-X's Boot Camp Assistant to restore your Win7 install. Otherwise, you might be able to use something like Ghost or other Windows imaging software. I'll have to leave it to some other reader to confirm whether that would work. WinClone has been 100% for me when moving or modifying Boot Camp partitions.

Even if Partition Magic can change the partition table to GUID without loss of data, I don't believe it will help. The way Apple did the dual boot is by simulating a MBR from within the GUID. That's what Boot Camp Assistant does when it creates the Windows partition.

To answer the size of an OS-X partition question: I have Snow Leopard installed in a 25GB partition with some tools, like Disk Warrior, for emergency and management use. SL and the basics (including Disk Warrior) took less than 11GB.

 

[gr8tfly]

Thank you for the excellent answer. I'll probably just bite the bullet and reinstall everything in a couple of months when Win7 final comes out.

Yep - that's probably the easiest way, unfortunately. Glad I was able to shed some light on the subject. Enjoy your new OS-X install!