Managing HP Serviceguard for Linux, Tenth Edition, September 2012

NOTE: Two of the central components of Serviceguard—Package Manager, and Cluster
Manager—run as parts of the cmcld daemon. This daemon runs at priority 94 and is
in the SCHED_RR class. No other process is allowed a higher real-time priority.
Log Daemon: cmlogd
cmlogd is used by cmcld to write messages to the system log file. Any message written
to the system log by cmcld it written through cmlogd. This is to prevent any delays in
writing to syslog from impacting the timing of cmcld. The path for this daemon is
$SGLBIN/cmlogd.
Network Manager Daemon: cmnetd
This daemon monitors the health of cluster networks. It also handles the addition and
deletion of relocatable package IPs, for both IPv4 and IPv6 addresses.
Lock LUN Daemon: cmdisklockd
If a lock LUN is being used, cmdisklockd runs on each node in the cluster, providing
tie-breaking services when needed during cluster re-formation. It is started by cmcld
when the node joins the cluster. The path for this daemon is $SGLBIN/cmdisklockd.
Cluster Object Manager Daemon: cmomd
This daemon is responsible for providing information about the cluster to clients—external
products or tools that depend on knowledge of the state of cluster objects.
Clients send queries to the object manager and receive responses from it (this
communication is done indirectly, through a Serviceguard API). The queries are
decomposed into categories (of classes) which are serviced by various providers. The
providers gather data from various sources, including, commonly, the cmclconfd
daemons on all connected nodes, returning data to a central assimilation point where it
is filtered to meet the needs of a particular query.
This daemon is started by xinetd. Parameters are in the /etc/xinetd.d/hacl-probe
file. The path for this daemon is $SGLBIN/cmomd.
This daemon may not be running on your system; it is used only by clients of the object
manager.
Service Assistant Daemon: cmserviced
This daemon forks and execs any script or processes as required by the cluster daemon,
cmcld. There are two type of forks that this daemon carries out:
• Executing package run and halt scripts
• Launching services
For services, cmcld monitors the service process and, depending on the number of
service retries, cmcld either restarts the service through cmsrvassistd or it causes
Serviceguard Architecture 35