Managing HP Serviceguard A.12.00.00 for Linux, June 2014

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 139), and in particular the subsection “Implications for
Application Deployment” (page 139).
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.
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 193) in the package configuration file 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
the others are available as backups. If one interface fails, another interface in the bonded group
takes over. HP strongly recommends you use channel bonding in each critical IP subnet to achieve
highly available network services.
Host Bus Adapters (HBAs) do not have to be identical. Ethernet LANs must be the same type, but
can be of different bandwidth (for example, 1 Gb and 100 Mb). Serviceguard for Linux supports
the use of bonding of LAN interfaces at the driver level. The Ethernet driver is configured to employ
a group of interfaces.
Once bonding is enabled, each interface can be viewed as a single logical link of multiple physical
ports with only one IP and MAC address. There is no limit to the number of slaves (ports) per bond,
and the number of bonds per system is limited to the number of Linux modules you can load.
You can bond the ports within a multi-ported networking card (cards with up to four ports are
currently available). Alternatively, you can bond ports from different cards. HP recommends that
use different cards.Figure 22 shows an example of four separate interfaces bonded into one
aggregate.
3.5 How the Network Manager Works 61