Section 2.6.1.1, “pulse” shows a detailed list of each software component in an LVS router.
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 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 router fails to respond after a user-configurable interval, it initiates failover. During failover, pulse on the backup router instructs the pulse daemon on the active router to shut down all LVS services, starts the send_arp program to reassign the floating IP addresses to the backup router's MAC address, and starts the lvs daemon.
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.
This service updates the IPVS routing table in the kernel. The lvs daemon sets up and administers an LVS cluster by calling ipvsadm to add, change, or delete entries in the IPVS routing table.
The nanny monitoring daemon runs on the active LVS router. Through this daemon, the active router determines the health of each real server and, optionally, monitors its workload. A separate process runs for each service defined on each real server.
This is the LVS cluster configuration file. Directly or indirectly, all daemons get their configuration information from this file.
This is the Web-based tool for monitoring, configuring, and administering an LVS cluster. This is the default tool to maintain the /etc/sysconfig/ha/lvs.cf LVS cluster configuration file.
This program sends out ARP broadcasts when the floating IP address changes from one node to another during failover.
Chapter 3, Initial LVS Configuration reviews important post-installation configuration steps you should take before configuring Red Hat Enterprise Linux to be an LVS router.