Expand disk for cluster

Good morning all...

We currently have a active/passive 2K cluster -- 100GB partition for data and another 100GB for backups. We just acquired another mass amount of databases from another division that we need to get online and running very soon, however we can't have a extensive outage of our cluster. PROBLEM: we need to expand the LUN on our SAN by another 150GB to accomodate for the new databases on the data partition, along with adding another 75GB on our backup partition.

Has anyone run into this situation where they are expanding their SAN to accomodate for growth? What did you do to minimize the downtime? Is it even possible? Or do I have to break the cluster, add the disk, rebuild the cluster and restore? GEESH, I hope not.

Thanks in advance!Refer to this link (http://www.sql-server-performance.com/clustering_intro2.asp) for more information.