Managing HP Serviceguard A.11.20.10 for Linux, December 2012

Because system multi-node and multi-node packages do not fail over, they do not have relocatable
IP address.
A relocatable IP address is like a virtual host IP address that is assigned to a package. HP
recommends that you configure names for each package through DNS (Domain Name System).
A program then can use the package’s name like a host name as the input to gethostbyname(3),
which will return the package’s relocatable IP address.
Relocatable addresses (but not stationary addresses) can be taken over by an adoptive node if
control of the package is transferred. This means that applications can access the package via its
relocatable address without knowing which node the package currently resides on.
IMPORTANT: Any subnet that is used by a package for relocatable addresses should be
configured into the cluster via NETWORK_INTERFACE and either STATIONARY_IP or
HEARTBEAT_IP in the cluster configuration file. For more information about those parameters,
see “Cluster Configuration Parameters ” (page 86). For more information about configuring
relocatable addresses, see the descriptions of the package ip_ parameters (page 176).
NOTE: It is possible to configure a cluster that spans subnets joined by a router, with some nodes
using one subnet and some another. This is called a cross-subnet configuration. In this context, you
can configure packages to fail over from a node on one subnet to a node on another, and you
will need to configure a relocatable address for each subnet the package is configured to start on;
see “About Cross-Subnet Failover” (page 125), and in particular the subsection “Implications for
Application Deployment” (page 126).
3.5.2 Types of IP Addresses
Both IPv4 and IPv6 address types are supported in Serviceguard. IPv4 addresses are the traditional
addresses of the form n.n.n.n where n is a decimal digit between 0 and 255. IPv6 addresses
have the form x:x:x:x:x:x:x:x where x is the hexadecimal value of each of eight 16-bit pieces
of the 128-bit address. You can define heartbeat IPs, stationary IPs, and relocatable (package) IPs
as IPv4 or IPv6 addresses (or certain combinations of both).
3.5.3 Adding and Deleting Relocatable IP Addresses
When a package is started, any relocatable IP addresses configured for that package are added
to the specified IP subnet. When the package is stopped, the relocatable IP address is deleted
from the subnet. These functions are performed by the cmmodnet command in the package master
control script (package control script for legacy packages).
IP addresses are configured only on each primary network interface card. Multiple IPv4 addresses
on the same network card must belong to the same IP subnet.
CAUTION: HP strongly recommends that you add relocatable addresses to packages only by
editing ip_address (page 177) in the package configuration file (or IP [] entries in the control
script of a legacy package) and running cmapplyconf (1m).
3.5.3.1 Load Sharing
Serviceguard allows you to configure several services into a single package, sharing a single IP
address; in that case all those services will fail over when the package does. If you want to be
able to load-balance services (that is, move a specific service to a less loaded system when
necessary) you can do so by putting each service in its own package and giving it a unique IP
address.
3.5.4 Bonding of LAN Interfaces
Several LAN interfaces on a node can be grouped together in a process known in Linux as channel
bonding. In the bonded group, typically one interface is used to transmit and receive data, while
60 Understanding Serviceguard Software Components