If the data center does not support FC storage, shared VMware vSAN resources or a deployed PowerFlex storage array, you can have storage over an IP network.
The supported storage resources can be either block-based or file system based. With block-level storage option, the LUN is presented to the VxRail cluster nodes over an IP network. VMware vSphere is used to configure a VMFS data store from the LUN.
iSCSI is a standard feature in VMware vSphere supported with VxRail. iSCSI is enabled by configuring a software adapter on a NIC on the VxRail nodes. The adapter then serves as an iSCSI initiator by targeting external storage arrays to present LUNs back to the initiators.
The NFS option also works over an IP network, except the storage presented back to the VxRail cluster is from a compatible file server, and the storage format is file-based instead of block-based. With this option, the external file system is mounted by the VxRail nodes to enable access over the IP network, and configured to serve as a data store.