I want to expand my startup disk space from 25gb to 40gb using this guide: http://blog.kyodium.net/2010/11/increase-disk-and-partition-size-in.html
But if I do umount /dev/disk0s2 as the article says then it says the disk is busy. If I do diskutil unmount /dev/disk0s2 like the terminal advices then it says it failed to unmount.
I can't go to disk utility and do this either because then it gives this message:
That's why I'm using this article that says you need to use the terminal to expand the disk instead and here is what I've tried: