Migrating from MDS9509 to MDS9710. MDS9710 document says it needs 3 fabrics

http://www.cisco.com/c/en/us/products/collateral/storage-networking/mds-9700-series-multilayer-directors/data_sheet_c78-727769.html

We are planning to migrate or do a hardware refresh from MDS9509 to MDS9710.

As of now our environment has only 1 vsan, We have purchased a fully populated MDS9710

I read in the product document (link above) that a minimum of three fabrics are required to support a fully populated chassis. What does this mean? how can we use this switch with just 1 vsan and as a stand alone switch?