Installation guide

58 Chapter 2. Red Hat Cluster Suite Component Summary
Function Components Description
LVS pulse This is the controlling process
which starts all other daemons
related to LVS routers. At boot
time, the daemon is started by the
/etc/rc.d/init.d/pulse
script. It then reads the
configuration file
/etc/sysconfig/ha/lvs.cf.
On the active LVS router, pulse
starts the LVS daemon. On the
backup router, pulse determines
the health of the active router by
executing a simple heartbeat at a
user-configurable interval. If the
active LVS router fails to respond
after a user-configurable interval, it
initiates failover. During failover,
pulse on the backup LVS router
instructs the pulse daemon on the
active LVS router to shut down all
LVS services, starts the send_arp
program to reassign the floating IP
addresses to the backup LVS
router’s MAC address, and starts
the lvs daemon.
lvsd The lvs daemon runs on the active
LVS router once called by pulse.
It reads the configuration file
/etc/sysconfig/ha/lvs.cf,
calls the ipvsadm utility to build
and maintain the IPVS routing
table, and assigns a nanny process
for each configured LVS service. If
nanny reports a real server is
down, lvs instructs the ipvsadm
utility to remove the real server
from the IPVS routing table.
ipvsadm This service updates the IPVS
routing table in the kernel. The lvs
daemon sets up and administers
LVS by calling ipvsadm to add,
change, or delete entries in the
IPVS routing table.