So, how do I do a clean install of ML?

[parish]

I've copied the ML installer to an external FW800 disk, booted from it, and let it install - but it's just done an upgrade of Lion that was installed.

I wanted to do a clean install but I didn't see any option for clean install vs. upgrade - in fact it said it was going to install, not upgrade, ML so I assumed it would be a clean install.

This is the first time I've wanted to do a clean install of OS X.

 

[appletechpro]

I've copied the ML installer to an external FW800 disk, booted from it, and let it install - but it's just done an upgrade of Lion that was installed.

I wanted to do a clean install but I didn't see any option for clean install vs. upgrade - in fact it said it was going to install, not upgrade, ML so I assumed it would be a clean install.

This is the first time I've wanted to do a clean install of OS X.

Format the disk in Disk Utility, then a clean installation will be performed.

 

[parish]

Format the disk in Disk Utility, then a clean installation will be performed.

Maybe I'm being thick, but how can you do that? It would mean formatting the disk OS X is running on - surely Disk Utility wouldn't allow you to do that.

 

[deeddawg]

Maybe I'm being thick, but how can you do that? It would mean formatting the disk OS X is running on - surely Disk Utility wouldn't allow you to do that.

You said you put the installer on an external disk and booted from that disk, right? No problem erasing the internal drive then, disk utility is available from the installer on the external disk.

I clean installed two systems; 2010 MBP13 into which I'd put a new SSD so it was a bare-metal install, and my 2011 MBA13 where I erased the SSD and installed.

 

[parish]

You said you put the installer on an external disk and booted from that disk, right? No problem erasing the internal drive then, disk utility is available from the installer on the external disk.

Ah, I didn't notice that, and I was looking out for an option to choose the type of install. I guess I'm thinking Windows which always gives you the option to add/delete partitions in the installer.

I'll try again and pay more attention.

Thanks for your help guys

 

[parish]

I've just re-run it and found Disk Utility - it's on the first screen the comes up. The reason I missed it is that it's at the bottom of the list but the second item on the list says

Reinstall OS X
Reinstall a new copy of OS X

and because it says 'new' I assumed it meant clean install so I didn't read any further.