Managing Serviceguard 11th Edition, Version A.11.16, Second Printing June 2004

Understanding Serviceguard Software Components
Serviceguard Architecture
Chapter 3 59
• /usr/lbin/cmsrvassistd—Serviceguard Service Assistant Daemon
• /usr/lbin/cmtaped—Serviceguard Shared Tape Daemon
• /usr/lbin/qs—Serviceguard Quorum Server Daemon
Each of these daemons logs to the /var/adm/syslog/syslog.log file
except for the quorum server, which logs to the standard output (it is
suggested you redirect output to a file named /var/adm/qs/qs.log) and
/opt/cmom/lbin/cmomd, which logs to /var/opt/cmom/cmomd.log.
Configuration Daemon: cmclconfd
This daemon is used by the Serviceguard commands to gather
information from all the nodes within the cluster. It gathers
configuration information such as information on networks and volume
groups. It also distributes the cluster binary configuration file to all
nodes in the cluster. This daemon is started by inetd(1M). There are
entries in the /etc/inetd.conf file.
Cluster Daemon: cmcld
This daemon is used to determine cluster membership by sending
heartbeat messages to other cmcld daemons on other nodes within the
Serviceguard cluster. It runs at a real time priority and is locked in
memory. The cmcld daemon sets a safety timer in the kernel which is
used to detect kernel hangs. If this timer is not reset periodically by
cmcld, the kernel will cause a system TOC, that is, a Transfer of Control,
which means a CPU reset and the creation of a crash dump file. This
could occur because cmcld could not communicate with the majority of
the cluster’s members, or because cmcld exited unexpectedly, aborted, or
was unable to run for a significant amount of time and was unable to
update the kernel timer, indicating a kernel hang. Before a TOC due to
the expiration of the safety timer, messages will be written to
/var/adm/syslog/syslog.log and the kernel’s message buffer.
The cmcld daemon also detects the health of the networks on the system
and performs local lan failover. Finally, this daemon handles the
management of Serviceguard packages, determining where to run them
and when to start them.
NOTE The three central components of Serviceguard—Package Manager,
Cluster Manager, and Network Manager—run as parts of the cmcld
daemon. This daemon runs at priority 20 on all cluster nodes. It is