HP Serviceguard for Linux Version A.11.18 Release Notes, 2nd Edition, March 2009

IMPORTANT: Although cross-subnet topology can be implemented on a single site,
it is most commonly used by extended-distance clusters.
Design and configuration of such clusters are covered in the disaster-tolerant
documentation delivered with Serviceguard. For more information, see the following
documents at http://www.docs.hp.com -> High Availability:
• Understanding and Designing Serviceguard Disaster Tolerant Architectures
• The white paper Technical Considerations for Creating a Serviceguard Cluster that
Spans Multiple IP Subnets
New Online Networking-Configuration Capabilities
You can now make significant changes to the cluster’s networking configuration while
the cluster is running.
What You Can Do
Online operations you can perform include:
• Add a network interface with its HEARTBEAT_IP or STATIONARY_IP.
• Delete a network interface with its HEARTBEAT_IP or STATIONARY_IP.
• Change the designation of an existing interface from HEARTBEAT_IP to
STATIONARY_IP, or vice versa.
• Change the NETWORK_POLLING_INTERVAL and
NETWORK_FAILURE_DETECTIONparameters.
• A combination of any of these in one transaction (cmapplyconf), given the
restrictions below.
What You Must Keep in Mind
The following restrictions apply:
• You must not change the configuration of all heartbeats at one time, or change or
delete the only configured heartbeat.
At least one working heartbeat, preferably with a standby, must remain unchanged.
• You cannot add interfaces or modify their characteristics unless those interfaces,
and all other interfaces in the cluster configuration, are healthy.
There must be no bad NICs or non-functional or locally switched subnets in the
configuration, unless you are deleting those components in the same operation.
• You cannot change the designation of an existing interface from HEARTBEAT_IP
to STATIONARY_IP, or vice versa, without also making the same change to all peer
network interfaces on the same subnet on all other nodes in the cluster.
32 Serviceguard for Linux Version A.11.18 Release Notes