How to safely install Ubuntu on an existing partition

Question

Sorry if this is a bit of a newbie question.

I'm trying to install the newest ubuntu desktop (11.10) on my MacBook Pro. I currently have two partitions, one 455 GB Mac OS partition, and one 45 GB NTFS partition.

My NTFS partition currently has Windows 7 on it, but I've come to the conclusion that linux/ubuntu would actually be more useful to have than Windows, so I want to overwrite my windows partition with Ubuntu.

I booted from my Ubuntu CD earlier, chose "Something else" from the install options (i.e. manual partition selection), but I got really worried about breaking something when I was presented with the partition window.

I figured out which one my Windows partition was, /dev/sda3 (I think), and I double-clicked that, and was presented with a dialog which said "use as"... and I wasn't quite sure what to select.

I also tried just selecting the partition and pressing "Install Now", but it gave me some error about the root filesystem.

Can someone give me some clear instructions on how to get the Ubuntu partition manager to use an existing partition for the install, without touching my other partition?

Answer 1

You were going down the right track when you selected "Something Else". At this point, you'll want to delete the 45 GB NTFS partition. It will be marked as free space. Select this free space and create a new ext3 partition in it, change the "Use As" combo box to read '/'. That means Ubuntu will use this partition as the root filesystem.