Managing HP Serviceguard for Linux, Eighth Edition, March 2008

Understanding Hardware Configurations for Serviceguard for Linux
Redundant Network Components
Chapter 2 31
• 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.
• Deploying applications in this environment requires careful
consideration; see“Implications for Application Deployment” on
page 137.
• 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
monitored for this package are configured for PARTIAL access, each
node on the node_name list must have at least one of these subnets
configured.
— As in other configurations, a package will not start on a node
unless the subnets configured on that node, and specified in the
package configuration file as monitored subnets, are up.
For More Information For more information on the details of
configuring the cluster and packages in a cross-subnet context, see
“About Cross-Subnet Failover” on page 136, “Obtaining Cross-Subnet
Information” on page 175, and (for legacy packages only) “Configuring
Cross-Subnet Failover” on page 286.