HP Serviceguard manual Cross-Subnet Configurations, Configuration Tasks, Restrictions

NOTE: You should verify that network traffic is not too heavy on the heartbeat/data LAN. If traffic is too heavy, this LAN might not perform adequately in transmitting heartbeats if the dedicated heartbeat LAN fails.

Cross-Subnet Configurations

As of Serviceguard A.11.18 it is possible to configure multiple subnets, joined by a router, both for the cluster heartbeat and for data, with some nodes using one subnet and some another.

A cross-subnet configuration allows:

•Automatic package failover from a node on one subnet to a node on another

•A cluster heartbeat that spans subnets.

Configuration Tasks

Cluster and package configuration tasks are affected as follows:

•You must use the -w full option to cmquerycl to discover actual or potential nodes and subnets across routers.

•You must configure two new parameters in the package configuration file to allow packages to fail over across subnets:

◦ip_subnet_node - to indicate which nodes the subnet is configured on

◦monitored_subnet_access - to indicate whether the subnet is configured on all nodes (FULL) or only some (PARTIAL)

(For legacy packages, see “Configuring Cross-Subnet Failover” (page 309).)

•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, and failing over across subnets can take longer.

List the nodes in order of preference rather than using the wildcard.

•You should configure IP monitoring for each subnet; see “Monitoring LAN Interfaces and Detecting Failure: IP Level” (page 73).

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.

•IPv6 heartbeat subnets are not supported in a cross-subnet configuration.

•IPv6–only and mixed modes are not supported in a cross-subnet configuration. For more information about these modes, see “About Hostname Address Families: IPv4-Only,IPv6-Only, and Mixed Mode” (page 106).

30 Understanding Serviceguard Hardware Configurations