[ovirt-users] change disk size using a thin provision based template

Hello, I am making some tests and this time I want to reduce the disk size before create a new vm (in the "new vm" window ) test: 1) click on "new VM" 2) select template (centos6.5 , 6GB, 500GB HD , 2 cores) 3) resource allocation : select "preallocated disk" 4) change disk size <<<< it is not possible ! Why I can not change disk size ? I know it is based on template who had already defined (500GB), but this template in fact has only 4GB of actual size in "thin provisioning" "allocation policy" . thanks tamer