Managing HP Serviceguard A.11.20.10 for Linux, December 2012

3.1.1.3 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.
3.1.1.4 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.
3.1.1.5 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.
3.1.1.6 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 the package to halt and
moves the package to an available alternate node. The path for this daemon is:
$SGLBIN/cmserviced.
3.1.1.7 Generic Resource Assistant Daemon: cmresourced
This daemon is responsible to set and get the status/value of generic resources configured as part
of the package and influence the availability of the package based on the availability of the
resource.
Generic resources allows integration of custom defined monitors in Serviceguard. It provides better
control, options, and flexibility in terms of getting and setting the status of a resource.
This daemon is used by the Serviceguard commands cmgetresource(1m) and
cmsetresource(1m) to get or set the status/value of a simple/extended generic resource
configured in a package and is local to a node. This daemon runs on every node on which cmcld
is running.
3.1.1.8 Quorum Server Daemon: qs
Using a quorum server is one way to break a tie and establish a quorum when the cluster is
re-forming; the other way is to use a Lock LUN. See “Cluster Quorum to Prevent Split-Brain
Syndrome” (page 38) and the sections that follow it.
The quorum server, if used, runs on a system external to the cluster. It is normally started from
/etc/inittab with the respawn option, which means that it automatically restarts if it fails or
is killed. It can also be configured as a Serviceguard package in a cluster other than the one(s) it
serves; see Figure 9 (page 40).
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 (system reset). For this reason it is important to bring the quorum server
back up as soon as possible.
For more information about the Quorum Server software and how it works, including instructions
for configuring the Quorum Server as a Serviceguard package, see the latest version of the HP
3.1 Serviceguard Architecture 33