The number of heartbeat datastores for host is 0, which is less than required: 2

Hello,

I'm having troubles creating my DRS cluster + DRS storage, i have 3 esxi 5.1 hosts for the task

First i created the cluster, no problems with that, then the storage DRS was created and now in the summary tab i can see

"The number of heartbeat datastores for host is 0, which is less than required: 2"

I've search the web and there are similar problems when people has only one datastore (the one that came with ESXi) and need to add another but in my case... vcenter detects none...

In the Storage Views i see the datastore (VMFS) but for some strange reason the cluster don't

In order to reach the minimum datastores (2) can i create an NFS and map it in ALL 3 esxi hosts?? Will vcenter consider that as a legit config?

Thanks