Red Hat CLUSTER SUITE FOR ENTERPRISE LINUX 5.2, Обзор

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A virtual server is a service configured to listen on a specific virtual IP.
Figure 1.20. Two-Tier LVS Topology
Service requests arriving at an LVS router are addressed to a virtual IP address or VIP. This is a
publicly-routable address that the administrator of the site associates with a fully-qualified
domain name, such as www.example.com, and which is assigned to one or more virtual
servers
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. Note that a VIP address migrates from one LVS router to the other during a failover,
thus maintaining a presence at that IP address, also known as floating IP addresses.
VIP addresses may be aliased to the same device that connects the LVS router to the public
network. For instance, if eth0 is connected to the Internet, then multiple virtual servers can be
aliased to
eth0:1
. Alternatively, each virtual server can be associated with a separate device
per service. For example, HTTP traffic can be handled on
eth0:1
, and FTP traffic can be
handled on
eth0:2
.
Only one LVS router is active at a time. The role of the active LVS router is to redirect service
requests from virtual IP addresses to the real servers. The redirection is based on one of eight
load-balancing algorithms:
Chapter 1. Red Hat Cluster Suite Overview
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