Managing HP Serviceguard A.11.20.00 for Linux, June 2012

The following constraints apply to peer polling when there are only two interfaces on a subnet:
• If one interface fails, both interfaces and the entire subnet will be marked down on each node,
unless bonding is configured and there is a working standby.
• If the node that has one of the interfaces goes down, the subnet on the other node will be
marked down.
• In a 2-node cluster, there is only a single peer for polling. When POLLING_TARGET is not
defined, if either of the nodes fail (For example, a node is rebooted or all the interfaces of a
node are down), IP monitoring fails and all the subnets are marked down on the operational
node. This results in failure of packages running on the operational node.
Therefore, peer polling is not suitable when there is only a single peer as exists in a 2-node
cluster. In such scenarios, a polling target should always be defined so that a single LAN
failure does not affect polling of other LANs.
Reporting Link-Level and IP-Level Failures
Any given failure may occur at the link level or the IP level; a failure is reported slightly differently
in the output of cmviewcl (1m) depending on whether link-level or IP monitoring detects the
failure.
If a failure is detected at the link level, output from cmviewcl -v will look like something like
this:
Network_Parameters:
INTERFACE STATUS PATH NAME
PRIMARY down (Link and IP) 0/3/1/0 eth2
PRIMARY up 0/5/1/0 eth3
cmviewcl -v -f line will report the same failure like this:
node:gary|interface:lan2|status=down
node:gary|interface:lan2|disabled=false
node:gary|interface:lan2|failure_type=link+ip
If a failure is detected by IP monitoring, output from cmviewcl -v will look like something like
this:
Network_Parameters:
INTERFACE STATUS PATH NAME
PRIMARY down (IP only) 0/3/1/0 eth2
PRIMARY up 0/5/1/0 eth3
cmviewcl -v -f line will report the same failure like this:
node:gary|interface:lan2|status=down
node:gary|interface:lan2|disabled=false
node:gary|interface:lan2|failure_type=ip_only
Package Switching and Relocatable IP Addresses
A package switch involves moving the package to a new system. In the most common configuration,
in which all nodes are on the same subnet(s), the package IP (relocatable IP; see “Stationary and
Relocatable IP Addresses and Monitored Subnets” (page 54)) moves as well, and the new system
must already have the subnet configured and working properly, otherwise the packages will not
be started.
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 117), and in particular the subsection“Implications for
Application Deployment” (page 118).
How the Network Manager Works 61