VSphere licenses and running hp VSA

Hi

I am in the planning stages for a customer and they've asked us to look at hp vsa vm running within vpshere to present the local storage of each host as shared storage. (2-3 hosts, 4TB storage, 6-8 VMs).  We're also considering the vsphere essential kit plus licenses to provide the virtual environment.  Do you know whether there is a minimum vsphere license required for hp's VSA?  All I can find in the VSA documentation is that vCentre is required so I assume vSphere essentials or essentials plus would be sufficient?

Any advice would be great - many thanks