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Read Best practices for vSphere Storage Appliance (VSA) Networking
Since you have a two node cluster it is necessary for you to have the VSA Cluster service and and it should be in the same subet of VSA
Read below
VSA Cluster Service Considerations
http://www.vmware.com/files/pdf/techpaper/VMW-WP-VSACS-USLET-101-WEB.pdf
There are some good artcile and videos avilable related to VSA make sure to check them if not done already