The default behavior of vSphere HA is to not automatically restart VMs if a host has been isolated. Host isolation means that the management network is no longer receiving heartbeats from other participants in the cluster. Once this occurs, the ESXi will ping the configured isolation address (by default the gateway address). If it cannot reach the gateway, the host considers itself isolated.
Everpure maintains no official recommendations for host isolation settings as this can be very environment specific. Though some considerations should be evaluated—an example of some important ones are below:
- If isolation response is enabled, and the storage is presented over the TCP/IP network (iSCSI) it is likely that a network partition of the host will also affect iSCSI access. So power-off and restart is likely the desired option since the VM will have lost its storage and a graceful power-off is not possible.
- If isolation response is enabled, and the storage is presented over Fibre Channel, shut down and restart VMs is likely the preferred option, as Fibre Channel access will likely persist in the event of TCP/IP network loss and a graceful shutdown will be the friendlier option.
- If the management network and the VM networks are physically the same equipment, it is likely that if one goes down, so do both. In this case, VMs often should be set to be restarted, especially if they need access to the network to run properly.
- If the VMs either do not need network access to run properly or the management network is physically separate from the VM network, enabling VM restart may not be the best idea as it will just introduce unnecessary downtime. In this case, it might just be a better idea to configure vCenter alerts for host isolation and fix the management network issue and let the VMs continue to run. For configuring vCenter alerts, refer to VMware documentation.