6.3

VMware, Inc. 9
Chapter 1 vCenter Server Heartbeat Introduction
Data Protection
vCenter Server Heartbeat intercepts all data written by users and applications, and maintains a copy of this
data on the passive server which is used in the event of a failure. vCenter Server Heartbeat configures itself to
protect files, folders, and even the registry settings for vCenter Server on the active server by replicating these
in near real-time to the passive server. If a server fails, all files protected on the failed server are available on
the Secondary server after a failover completes.
Communications
vCenter Server Heartbeat Communications
vCenter Server Heartbeat Primary and Secondary servers communicate with one another via the VMware
Channel which is used for control and data transfer. Clients connect to vCenter Server and vCenter Server
Heartbeat using the Principal (Public) network.
VMware Channel
The VMware Channel is a dedicated communications link for control and data replication between the active
and passive servers. The VMware Channel operates independently from the Principal (Public) network that
services clients. The VMware Channel consists of a dedicated NIC on each of the two servers configured to
communicate with only the other server’s VMware Channel NIC. When required, static routing can be used
to direct traffic to the other server. A second pair of NICs is recommended in order to provide a degree of
redundancy for the VMware Channel. The NICs on the active and passive servers used for the VMware
Channel are normally configured so that their IP addresses are outside of the subnet range of the Principal
(Public) network. These addresses are referred to as VMware Channel addresses as illustrated above.
Principal (Public) Network
Users connect to vCenter Server Heartbeat using the Principal (Public) network. For communications with the
Principal (Public) network, each server in the Pair must have at least one dedicated NIC on the Primary (active)
server and one dedicated NIC on the Secondary (passive) server. The NIC on the passive server is configured
to use the same IP address as that of the active server but is prevented from communicating with the live
network through an IP packet filtering system installed with vCenter Server Heartbeat. This packet filter
prevents traffic using the Principal (Public) address from being committed to the wire. It also prevents
NetBIOS traffic utilizing other IP addresses on the NIC from being sent to prevent NetBIOS name resolution
conflicts.