6.5

Table Of Contents
A name conict occurs on a server pair running vCenter Server Heartbeat. In a WAN environment the
Primary and Secondary servers connect to the network using dierent IP addresses. However, if the servers
are running with the same name and are visible to each other across the WAN, a name conict occurs
Clients (for example, VI Client, ESX, etc.) cannot connect to the server running vCenter Server Heartbeat
Cause
The most common causes of two active servers (Split-brain syndrome) are as follows:
Loss of the VMware Channel connection (most common in a WAN environment)
The active server is too busy to respond to heartbeats
Incorrect conguration 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 server with the most up-to-date data
To resolve Split-brain syndrome, identify the server with the most up-to-date data. If you identify the wrong
server you risk losing data. You must reinstate the correct server.
Check the date and time of les on both servers. Make the most up-to-date server the active server.
From a client PC on a LAN, run nbtstat -A 192.168.1.1 where the IP address is the Principal (Public) IP
address of the server. This can help identify the MAC address of the server currently visible to client
machines.
Note If both active servers were servicing clients, perhaps at dierent WAN locations, you can make
only one server active. Both servers contain recent data that cannot be merged using vCenter Server
Heartbeat. To restart replication, make one server active and one server passive. When replication restarts,
the active server overwrites all data on the passive server. You can manually extract the up-to-date data
from the passive server 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 servers (Split-brain syndrome)
The following procedure corrects two active servers and results in an active and passive server pair.
1 Identify the server with the most up-to-date data or the server to make active.
2 Shut down vCenter Server Heartbeat on both servers (if running).
3 On the server to make passive, right-click the Task bar icon, and select the Server Conguration wizard.
4 Select the Machine tab and set the server role to passive. Do not change the identity of the server (Primary
or Secondary).
5 Click Finish.
6 Restart this server.
7 Start vCenter Server Heartbeat, if required, and check that the Task bar icon now reects the changes by
showing P / - (Primary and Passive) or S / - (Secondary and Passive).
8 On the active server, right-click the Task bar icon and select the Server Conguration wizard.
9 Select the Machine tab and verify that the server role is set to active. Do not change the identity of the
server (Primary or Secondary).
10 Click Finish.
84 VMware, Inc.
Administrator Guide