A vSphere 4.0 VMware High Availability cluster may not failover virtual machines when ESX is configured with certain IP addresses – KB Article: 1013013

A new KB from VMware was released on the 20th.

Here are the details.

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Symptoms

You experience these symptoms:

• In vCenter 4.0, VMware HA might not failover virtual machines when a host failure occurs.
• When the ESX host’s IP address in a VMware HA enabled cluster is configured with certain IP addresses, the node failure detection algorithm fails.
• You are susceptible to this issue when all of your Service Console Port(s) or Management Network IP address(s) on your ESX host fall within the following range:
  3.x.x.x – 9.x.x.x
  26.x.x.x – 99.x.x.x

Note: You are not affected if one of Service Console Port(s) or Management Network IP address(s) on your ESX host falls outside of this range.

Resolution

Switch the Service Console Port(s) or Management Network IP address(s) on your ESX host in the VMware HA cluster to IP ranges that do not fall within the affected range. For example, 10.x.x.x or 192.168.x.x.

If you have multiple Service Console or Management networks, at least one of your networks must be outside of the affected range. VMware HA still uses the affected range for cluster communication and heartbeating but not for host failure verification.

If changing the IP address(s) of your Service Console Port(s) or Management Network(s) is not possible, you can also install vCenter Server 4.0 Patch 1.”