Chapter 13: The LVS-DR Cluster

Overview

The Linux Virtual Server Direct Routing (LVS-DR) cluster is made possible by configuring all nodes in the cluster and the Director with the same VIP address; despite having this common address, though, client computers will only send their packets to the Director.

The Director can, therefore, balance the incoming workload from the client computers by using one of the LVS scheduling methods we looked at in Chapter 12.

The LVS-DR cluster configuration that we use in this chapter assumes that the Director is a computer dedicated to this task. In Chapter 14 we'll take a closer look at what is going on inside this computer, and in Chapter 15 we'll see how the load-balancing resource^[1] can be placed on a real server and made highly available using the Heartbeat package.

But before we build an enterprise-class, highly available LVS-DR cluster (in Chapter 15), let's examine how the LVS-DR forwarding method works in more detail.

^[1]Recall from our discussion of Heartbeat in Chapter 6 that a service, along with its associated IP address, is known as a resource. Thus, the virtual services offered by a Linux Virtual Server and their associated VIPs can also be called resources in high-availability terminology.