Managing Serviceguard Sixteenth Edition, March 2009

• You should not use the wildcard (*) for node_name in the package configuration
file, as this could allow the package to fail over across subnets when a node on the
same subnet is eligible. Instead, list the nodes in order of preference.
• You should configure IP monitoring for each subnet; see “Monitoring LAN
Interfaces and Detecting Failure: IP Level” (page 99).
Restrictions
The following restrictions apply:
• All nodes in the cluster must belong to the same network domain (that is, the
domain portion of the fully-qualified domain name must be the same).
• The nodes must be fully connected at the IP level.
• A minimum of two heartbeat paths must be configured for each cluster node.
• There must be less than 200 milliseconds of latency in the heartbeat network.
• 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:
— The heartbeats must be statically routed; static route entries must be configured
on each node to route the heartbeats through different paths.
— Failure of a single router must not affect both heartbeats at the same time.
• Because Veritas Cluster File System from Symantec (CFS) requires link-level traffic
communication (LLT) among the nodes, Serviceguard cannot be configured in
cross-subnet configurations with CFS alone.
But CFS is supported in specific cross-subnet configurations with Serviceguard
and HP add-on products; see the documentation listed below.
• Each package subnet must be configured with a standby interface on the local
bridged net. The standby interface can be shared between subnets.
• Deploying applications in this environment requires careful consideration; see
“Implications for Application Deployment” (page 189).
• cmrunnode will fail if the “hostname LAN” is down on the node in question.
(“Hostname LAN” refers to the public LAN on which the IP address that the node’s
hostname resolves to is configured).
• If a monitored_subnet is configured for PARTIAL monitored_subnet_access in a
package’s configuration file, it must be configured on at least one of the nodes on
the node_name list for that package. Conversely, if all of the subnets that are being
42 Understanding Serviceguard Hardware Configurations