You must have one cluster shared volume (CSV) for every VD. You must add CSVs in multiples of the storage nodes to allow for the CSVs to be load balanced across the cluster.
For example, if you have a 2x2 configuration, which has two storage nodes, you should create CSVs in multiples of 2 (for example 2, 4, 6, and 8 CSVs). If you have a 4x4 configuration which has 4 storage nodes, then you should create CSVs in multiples of 4 (for example 4, 8, 12, and 16 CSVs). For optimal performance, Dell recommends having at least twice the number of CSVs as storage nodes. In this example, at a minimum, a 2x2 configuration would optimally have four CSVs.