I wrote this article about split brain scenarios for the vSphere Blog. Based on this article I received some questions around which “isolation response” to use. This is not something that can be answered by a simple “recommended practice” and applied to all scenarios out there. Note that below has got everything to do with your infrastructure. Are you using IP-Based storage? Do you have a converged network? All of these impact the decision around the isolation response.
The following table however could be used to make a decision:
|Likelihood that host will retain access to VM datastores||Likelihood that host will retain access to VM network||Recommended Isolation policy||Explanation|
|Likely||Likely||Leave Powered On||VM is running fine so why power it off?|
|Likely||Unlikely||Either Leave Powered On or Shutdown||Choose shutdown to allow HA to restart VMs on hosts that are not isolated and hence are likely to have access to storage|
|Unlikely||Likely||Power Off||Use Power Off to avoid having two instances of the same VM on the VM network|
|Unlikely||Unlikely||Leave Powered On or Power Off||Leave Powered on if the VM can recover from the network/datastore outage if it is not restarted because of the isolation, and Power Off if it likely can’t.|