Managing Serviceguard 13th Edition, February 2007

Understanding Serviceguard Software Components
Serviceguard Architecture
Chapter 3 63
The quorum server, if used, runs on a system external to the cluster and
is started by the system administrator, not by Serviceguard. It is
normally started from /etc/inittab with the respawn option, which
means that it automatically restarts if it fails or is killed. All members of
the cluster initiate and maintain a connection to the quorum server; if it
dies, the Serviceguard nodes will detect this and then periodically try to
reconnect to it. If there is a cluster re-formation while the quorum server
is down and tie-breaking is needed, the re-formation will fail and all the
nodes will halt (TOC). For this reason it is important to bring the
quorum server back up as soon as possible.
Network Sensor Assistant daemon cmnetassistd
The network sensor assistant daemon handles addition and deletion of
relocatable package IP(s), for both IPv4 and IPv6 addresses.
CFS Components
The HP Serviceguard Storage Management Suite offers additional
components for interfacing with the VERITAS Cluster File System on
some current versions of HP-UX (see “About VERITAS CFS and CVM”
on page 27). Documents for the management suite are posted on
http://docs.hp.com.
VERITAS CFS components operate directly over Ethernet networks that
connect the nodes within a cluster. Redundant networks are required to
avoid single points of failure.
The VERITAS CFS components are:
• GAB (Group Membership Services/Atomic Broadcast) - When
VERITAS Cluster Volume Manager (CVM) 4.1 or VERITAS Cluster
File System (CFS) is deployed as part of the Serviceguard Storage
Management Suite bundles, the file /etc/gabtab is automatically
configured and maintained by Serviceguard.
GAB provides membership and messaging for CVM and the CFS.
GAB membership also provides orderly startup and shutdown of the
cluster file system.
• LLT (Low Latency Transport) - When VERITAS CVM or CFS is
deployed as part of the Serviceguard Storage Management Suite
bundles, the LLT files /etc/llthosts and /etc/llttab are
automatically configured and maintained by Serviceguard.