VirtuCache doesn’t support Write-Back caching for a cluster with mixed ESXi 6.x and 7.x hosts

Because VirtuCache uses different APIs for ESXi 6.x and 7.x, VirtuCache cannot establish peer connections between hosts that are on ESXi 6.x and 7.x, as a result, VirtuCache cannot replicate (mirror) the write cache between hosts that are on ESXi 6.x and 7.x, and so VirtuCache’s ‘Write-Back 1 Replica’ policy will not work in a cluster that has mixed 6.x and 7.x hosts.
This constraint doesn’t apply to dot releases within ESXi 6 or ESXi 7 i.e VirtuCache fully supports all features if the ESXi cluster has hosts on different versions of ESXi 6.x in the same cluster.