Adequate storage is a necessity when you’re clustering SQL Server. Mount points can provide you with extra drive space and I/O capacity. You can create mount points by creating an empty folder within a drive. Then use the Computer Management tool to assign an unused volume to be mounted to that folder. For example, say that the shared drive will be E, and you decide that the E drive needs more space but you don’t want to extend the drive. You can instead create a folder in the E drive named E:\mnt1\. Then assign a LUN from the SAN, align it as you typically would, and create the partition. Then mount the partition to E:\mnt1\. When you open the E drive, you won’t see a drive letter within the drive window because this is your mount point.
When working with mount points within a cluster, you need to get the precedence order correct in the Cluster Administrator window. To do so, add the volume that’s being mounted as E:\mnt1\ as a clustered resource within the cluster group. Then configure the new resource to be dependent on the cluster resource that points to the E drive. You’ll also want to make sure that the SQL Server service is dependent on the mount point as well as the E drive; otherwise, the SQL Server might try to start before the mount point has been completely loaded.