To my surprise CentOS 7 is now using XFS. I was trying to extend the LVM using my usual guide from VMware, resize2fs command spits out thi error:
resize2fs: Bad magic number in super-block while trying to open /dev/centos/root Couldn't find valid filesystem superblock
use xfs_grow instead
http://xmodulo.com/2014/09/manage-lvm-volumes-centos-rhel-7-system-storage-manager.html