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Chapter 1 Introduction
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. The mechanics of switchovers are discussed in more detail later in this guide.
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.
vCenter Server Heartbeat provides the same level of flexibility to define and perform multiple corrective
actions in the event of problems on a service by service or even attribute by attribute basis.
Data Protection
You can configure vCenter Server Heartbeat to protect the application environment. All data files that users
or the applications require in the application environment are made available should a failure occur. After
installation, vCenter Server Heartbeat configures itself to protect files, folders, and registry settings for
vCenter Server on the active server by mirroring them in real time to the passive server. If a failover occurs,
all files protected on the failed server are available to users after the failover, hosted on the Secondary server.
vCenter Server Heartbeat intercepts all file system I/O operations on the active server. If the intercepted write
and update operations are within the protected set, these are placed in a queue on the active server referred to
as the active server’s send queue, pending transmission to the passive server. Each request is numbered to
maintain its order in the queue.
With the request in the active server’s send queue, vCenter Server Heartbeat allows the disk I/O to continue
with the requested disk operation.
If the channel is connected, the active server’s send queue is transferred to the passive server, which places all
the requests in the passive server’s receive queue. The passive server confirms the changes were logged by
sending the active server an acknowledgement. The active server clears the data from its queue.