Managing HP Serviceguard for Linux, Tenth Edition, September 2012

NOTE: This applies only to hostname resolution. You can have IPv6 heartbeat and
data LANs no matter what the HOSTNAME_ADDRESS_FAMILY parameter is set to. (IPv4
heartbeat and data LANs are allowed in IPv4 and mixed mode.)
What Is IPv6-Only Mode?
If you configure IPv6-only mode (HOSTNAME_ADDRESS_FAMILY set to IPV6, or
cmquerycl -a ipv6), then all the hostnames and addresses used by the cluster —
including the heartbeat and stationary and relocatable IP addresses, and Quorum Server
addresses if any — must be or resolve to IPv6 addresses. The single exception to this is
each node's IPv4 loopback address, which cannot be removed from /etc/hosts.
NOTE: How the clients of IPv6-only cluster applications handle hostname resolution is
a matter for the discretion of the system or network administrator; there are no HP
requirements or recommendations specific to this case.
In IPv6-only mode, all Serviceguard daemons will normally use IPv6 addresses for
communication among the nodes, although local (intra-node) communication may occur
on the IPv4 loopback address.
For more information about IPv6, see Appendix D (page 328).
Rules and Restrictions for IPv6-Only Mode
IMPORTANT: See the latest version of the Serviceguard for Linux release notes for the
most current information on these and other restrictions.
• Red Hat 5 clusters are not supported.
NOTE: This also applies if HOSTNAME_ADDRESS_FAMILY is set to ANY; Red Hat
5 supports only IPv4-only clusters.
• All addresses used by the cluster must be in each node's /etc/hosts file. In
addition, the file must contain the following entry:
::1 localhost ipv6-localhost ipv6-loopback
For more information and recommendations about hostname resolution, see
“Configuring Name Resolution” (page 159).
• All addresses must be IPv6, apart from the node's IPv4 loopback address, which
cannot be removed from /etc/hosts.
• The node's public LAN address (by which it is known to the outside world) must be
the last address listed in /etc/hosts.
Otherwise there is a possibility of the address being used even when it is not
configured into the cluster.
Cluster Configuration Planning 101