vCenter Server 4.0 Patch 1

Don’t think many people have noticed this KB article yet or even experienced this issue with HA but nevertheless it’s worth mentioning. Apparently there’s an issue with HA in vCenter 4.0 when a class A network is being used. When a node fails this will not be detected and thus the fail-over of VMs will not occur. Although not many customers are using these class A ranges it is something I think you all should be aware of. This issue has been resolved and VMware released the following KB article which contains a link to the patch:

http://kb.vmware.com/kb/1013013
A vSphere 4.0 VMware High Availability cluster may not failover virtual machines when ESX is configured with certain IP addresses

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.