6.6

Two Active or Two Passive Nodes
Should both nodes (Primary and Secondary) become active or passive at the same time, you should address
the issue immediately.
Two Active Nodes
Two active nodes live on the same network is critical and referred to as Split-brain syndrome.This condition
must be resolved immediately.
Problem
Split-brain syndrome is identified by the following symptoms:
■
Both nodes in a pair are running and in an active state.The task bar icons display P / A (Primary and
active) and S / A (Secondary and active)
■
An IP address conflict occurs on a pair running vCenter Server Heartbeat on the Public IP address in a
LAN
■
In a WAN environment the Primary and Secondary connect to the network using different IP addresses.
■
Clients (for example, vSphere Client and vSphere Web Client) cannot connect to the node running vCenter
Server Heartbeat
Cause
The most common causes of two active nodes (Split-brain syndrome) are as follows:
■
Loss of the VMware Channel connection (most common in a WAN environment)
■
The active node is too busy to respond to heartbeats
■
Incorrect configuration of the vCenter Server Heartbeat software
You must determine the cause of the Split-brain syndrome and resolve the issue to prevent this condition from
recurring.
Solution
Identifying the node with the most up-to-date data
To resolve Split-brain syndrome, identify the node with the most up-to-date data. If you identify the wrong node
you risk losing data.You must reinstate the correct node.
■
Check the date and time of files on both nodes. Make the most up-to-date node the active node.
■
From a client PC on a LAN, run nbtstat -A 192.168.1.1 where the IP address is the Public IP address of the
node.This can help identify the MAC address of the node currently visible to client machines.
Note If both active nodes were servicing clients, perhaps at different WAN locations, you can make only
one node active. Both nodes contain recent data that cannot be merged using vCenter Server Heartbeat.
To restart replication, make one node active and one node passive. When replication restarts, the active
node overwrites all data on the passive node.You can manually extract the up-to-date data from the
passive node prior to restarting replication. Consult the Microsoft Knowledge Base for information on
various tools for this purpose. For further information, contact your VMware support representative.
Resolving two active nodes (Split-brain syndrome)
80 VMware, Inc.
vCenter Server Heartbeat Administrator's Guide