Managing HP Serviceguard A.11.20.20 for Linux, May 2013

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 285).
4.7.3.2.1 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 and Red Hat 6 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 137).
• 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.
• You must use $SGCONF/cmclnodelist, not ~/.rhosts or /etc/hosts.equiv, to
provide root access to an unconfigured node.
NOTE: This also applies if HOSTNAME_ADDRESS_FAMILY is set to ANY. See “Allowing
Root Access to an Unconfigured Node” (page 136) for more information.
• If you use a Quorum Server, you must make sure that the Quorum Server hostname (and the
alternate Quorum Server address specified by QS_ADDR, if any) resolve to IPv6 addresses,
and you must use Quorum Server version A.04.00 or later. See the latest Quorum Server
release notes for more information; you can find them at http://www.hp.com/go/
linux-serviceguard-docs.
NOTE: The Quorum Server itself can be an IPv6–only system; in that case it can serve
IPv6–only and mixed-mode clusters, but not IPv4–only clusters.
• If you use a Quorum Server, and the Quorum Server is on a different subnet from cluster, you
must use an IPv6-capable router.
• Hostname aliases are not supported for IPv6 addresses, because of operating system limitations.
4.7 Cluster Configuration Planning 89