move hosts to new partition

[circuithead]

recently got a new server from provider. the hd is partitioned up some, but the bulk of the hard drive is on a different partition than is being shown in the stats for /var/www/vhosts

can i just unmount and remount the directory in the shell? and leave the other stuff in the smaller hda (the psa, mysql, etc). or is it more complicated than that because of plesk?