When you build a new Microsoft Cluster Server cluster always be sure to fail over all the drives between all the nodes before installing SQL Server on it and deploying the cluster to production. The first time that you fail over a cluster from one node to another the disks can take a very long time to fail over.
If you don’t test this fail over ahead of time your first production fail over could be quite a bit longer than you expect. Granted I’m only talked 30-60 seconds longer than expected, but your are clustering the SQL Server for the most possible uptime, and 30-60 extra seconds could be a big problem.
Do in other words test, then deploy.