6.5

Rule
A set of actions performed by vCenter Server Heartbeat when dened conditions are met.
Secondary
An identity assigned to a server during the vCenter Server Heartbeat installation process that normally
does not change during the life of the server and usually represents the standby server prior to installation
of vCenter Server Heartbeat.
Security Identier (SID)
A unique alphanumeric character string that identies each operating system and each user in a network
of 2003/2008 systems.
Send Queue
The staging area on a server used to store intercepted data changes before being transported across to a
passive server in the replication chain.
Server Monitoring
Monitoring of the active server by the passive server, using a heartbeat message, to ensure that the active
server is functional.
Shared Nothing
A key feature of vCenter Server Heartbeat in which no hardware is shared between the Primary and
Secondary servers. This prevents a single point of failure.
SMTP
A TCP/IP protocol used in sending and receiving e-mail between servers.
SNMP
Simple Network Management Protocol (SNMP) is an Internet-standard protocol for managing devices on
IP networks.
Split-Brain Avoidance
A unique feature of vCenter Server Heartbeat that prevents a scenario in which Primary and Secondary
servers attempt to become active at the same time leading to an active-active rather than an active-passive
model.
Split-Brain Syndrome
A situation in which more than one server in a vCenter Server Heartbeat Cluster are operating in the active
mode and attempting to service clients, resulting in the independent application of dierent data updates
to each server.
Subnet
Division of a network into an interconnected but independent segment or domain, intended to improve
performance and security.
Storage Area Network (SAN)
A high-speed special-purpose network or (sub-network) that interconnects dierent kinds of data storage
devices with associated data servers on behalf of a larger network of users.
Switchover
The graceful transfer of control and application service to the passive server.
Synchronize
The internal process of transporting 64KB blocks of changed les or registry key data, through the VMware
Channel, from the active server to the passive server to ensure the data on the passive server is a mirror
image of the protected data on the active server.
System Center Operations Manager (SCOM)
System Center Operations Manager is a cross-platform data center management server for operating
systems and hypervisors.
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Glossary