Installation guide

VMware, Inc. 11
Chapter 1 Introduction
Network Protection
vCenter Server Heartbeat proactively monitors the network by polling up to three nodes to ensure that the
active server is visible on 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 the same role
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) to verify that protected applications are operational
and not in an unresponsive or stopped state. This level of monitoring is fundamental in ensuring that
applications remain available to users.
If a protected application fails, vCenter Server Heartbeat first tries to restart the application on the active server
(1) in Figure 1-2.
If the application does not successfully restart, vCenter Server Heartbeat initiates a switchover (2) in
Figure 1-2. Refer to “vCenter Server Heartbeat Switchover and Failover Processes” on page 13 for further
information about the switchover process.
Figure 1-2. Switchover
A switchover gracefully closes any protected applications that are running on the active server and restarts
them on the passive server, including the application or service that caused the failure. In the example where
the Primary server is active and the Secondary server is passive, the Primary server is demoted to a passive
role and is hidden from the network when the Secondary server is promoted to an active role and is made
visible to the network.
Performance Protection
Ensuring that your protected applications are operational and providing service at a level of performance
adequate for users to remain productive is important. The vCenter Server Heartbeat plug-in provides these
monitoring and pre-emptive repair capabilities.
vCenter Server Heartbeat proactively monitors system performance attributes to ensure that the system
administrator is notified of problems and can take pre-emptive action to prevent an outage.
In addition to monitoring application services, vCenter Server Heartbeat can 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.