I've received a request to add disaffinity/anti-affinity rules on a set of virtual machines in a VMware HA/DRS cluster running VMware vSphere 4.1.
The client has four hosts and wants to keep certain virtual machines from running on the same host in the event of a host failure.
Normally, this type of request is straightforward, where you can simply avoid running app01 and app02 on the same machine... There's an separate application load balancer upstream.
However, this request asks for app01, app02, app03, app04, app05 and app06 to run on different hosts.
Six VM's, four hosts. Our first-response team added app01-app06 into a single "Separate Virtual Machines" DRS rule. This does not seem right because the results could be unpredictable in a maintenance mode or Upgrade Manager remediation.
What is the impact of doing so with four hosts? Will this achieve the desired goal? Downsides?