For those of you trying to install Windows OS via Bootcamp on an internal drive other than your MacOS boot volume, AND who want to do so on a partition already created by Disk Utility, i have some news for you,... you can't. 
Not without losing all your data that is.
If you want to have Windows OS installed on a partition, Bootcamp has to create that partition itself, Disk Utility cannot. So,.. make the disk ONE partition and then you'll be able to select the previously grayed out "create a second partition..." option in the Bootcamp Assistant menu.
I know this probably seems obvious to most of you but i couldn't figure it out and couldn't find info on it to solve my issues - especially in apple docs - so i decided to post a hopefully informative thread. Mostly because i wanted to install WINDOWS on an already created partition - BOOTCAMP WON'T LET YOU DO THAT.
Sounds simple,.. i know. But when you're dead set on keeping the partition you've already created,.. it's hard to see the obvious simple solution.
Not without losing all your data that is.If you want to have Windows OS installed on a partition, Bootcamp has to create that partition itself, Disk Utility cannot. So,.. make the disk ONE partition and then you'll be able to select the previously grayed out "create a second partition..." option in the Bootcamp Assistant menu.
I know this probably seems obvious to most of you but i couldn't figure it out and couldn't find info on it to solve my issues - especially in apple docs - so i decided to post a hopefully informative thread. Mostly because i wanted to install WINDOWS on an already created partition - BOOTCAMP WON'T LET YOU DO THAT.
Sounds simple,.. i know. But when you're dead set on keeping the partition you've already created,.. it's hard to see the obvious simple solution.