If you made a dynamic disk before you created any volumes, it's no problem. Just expand the LUN in the EVA, do a rescan and new, unused space should appear. Just right click on the volume and select expand. Done.
If the disk is basic, you can convert it to dynamic without data loss. _However_ you can't expand the volume if you have partitions created before the conversion.
If you have a cluster, you have per definition basic disks since dynamic disks aren't supported in a cluster.
In either of those cases, I think you can expand the volume without data loss with the diskpart utility (downloadable from Microsoft). You might have to stop all access to the disk, but you needn't reboot the server.
/charles
