Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Planning and Documenting an HA Cluster
Cluster Configuration Planning
Chapter 4114
Heartbeat configuration requirements:
The cluster needs at least two network interfaces for
the heartbeat in all cases, using one of the following
minimum configurations:
• two heartbeat subnets; or
• one heartbeat subnet using bonding in high
availability mode (or mode 1) with two slaves.
NOTE The Serviceguard cmapplyconf, cmcheckconf, and
cmquerycl commands check that these minimum
requirements are met, and produce a warning if they
are not met at the immediate network level. If you see
this warning, you need to check that the requirements
are met in your overall network configuration.
If you are using virtual machine guests as nodes, you
have a valid configuration (and can ignore the warning)
if there is one heartbeat network on the guest, backed
by a network on the host using APA with two trunk
members (HPVM), or using NIC bonding as in the
second bullet above (VMware ESX Server).
Considerations for cross-subnet:
IP addresses for a given heartbeat path are usually on
the same subnet on each node, but it is possible to
configure the heartbeat on multiple subnets such that
the heartbeat is carried on one subnet for one set of
nodes and another subnet for others, with the subnets
joined by a router.
This is called a cross-subnet configuration, and in
this case at least two heartbeat paths must be
configured for each cluster node, and each heartbeat
subnet on each node must be physically routed
separately to the heartbeat subnet on another node
(that is, each heartbeat path must be physically
separate).
See “Cross-Subnet Configurations” on page 30.