5.5

QuickStart Guide
8 VMware, Inc.
A failover is similar to a switchover but is used in more urgent situations, such as when the passive server
detects that the active server is no longer responding. This can occur when the active server hardware fails,
loses its network connections, or otherwise becomes unavailable. Rather than the active server gracefully
closing, the passive server determines that the active server has failed and requires no further operations. In a
failover, the passive server immediately assumes the active server role.
Network Protection
vCenter Server Heartbeat proactively monitors the active server to verify that it can communicate with the rest
of the network. vCenter Server Heartbeat polls defined nodes around the network, including the default
gateway, the primary DNS server, and the global catalog server at regular intervals. If all three nodes fail to
respond, for example, in the case of a network card failure or a local switch failure, vCenter Server Heartbeat
can initiate a switchover, allowing the Secondary server to assume an identical network identity as the Primary
server.
Application Protection
vCenter Server Heartbeat running on the active server locally monitors the applications and services it has
been configured to protect through the use of plug-ins.
If a protected application fails, vCenter Server Heartbeat first tries to restart the application on the active server
(1). If restarting the application fails, then vCenter Server Heartbeat can initiate a switchover (2).
Figure 1-2. Switchover
A switchover gracefully closes any protected applications that are running on the active server and restarts all
of them on the passive server, including the application or service that caused the failure as illustrated in
Figure 1-2.
Performance Protection
vCenter Server Heartbeat monitors application services and specific application attributes to ensure that
protected applications are operational and not in an unresponsive or stopped state. This level of monitoring is
fundamental in ensuring that applications are available to users.
In addition to monitoring application services, vCenter Server Heartbeat can also monitor specific application
attributes to ensure that they remain within normal operating ranges. Similar to application monitoring,
various rules can be configured to trigger specific corrective actions whenever these attributes fall outside of
their respective ranges.