you have 3 consecutive partitions forming a raid0 array?? what is the possible logical benefit of doing that?
you have no extra resiliency, no extra io benefits from multiple devices... that's useless. if you need more space i'd probably just increase one of those partitions using resie2fs if it's an ext3 partition, but i guess that you'll be able to use something like raidhotadd, or mdadm (e.g. mdadm /dev/md0 --add /dev/hda9) to add if it has been configured as a genuine raid0. but again, be aware how pointless that raid setup actually is... maybe you're actaully after the benefits of an LVM filesystem and not raid?