I'm installing CentOS on a system that has pre-defined partitions (XFS, created by Ubuntu 14.04 Live CD).  I can select the little 500MB partition and give it a mount point of /boot no problem.  When I select the larger partition and set a mount point of /, it doesn't stick... no matter what I do, it will not retain that.I was able to delete that partition and then create a new one that was slightly smaller, but that is saying the new partition will be /dev/sda10, and the one I removed was /dev/sda9 and I had a /dev/sda10 already, so I hope that one wasn't destroyed!I really hate the partitioning tool in CentOS 7's installer more each time I use it...
CentOS install - select existing partition as /
centos;partition