3.6.0 Matrix Server 3.6.0 Administration Guide (5697-7081, December 2007)

Chapter 5: Configure Servers 52

then access the original server name will actually be served by the

virtual host—basically, a failover-protected version of the server, with

no difference in appearance to the clients.

• Keep the existing name on the server. If you do not rename the

server, clients will need to use the new virtual host name to benefit

from failover protection. Clients can still access the server by its name,

but those requests are not protected by Matrix Server. If the server

fails, requests to the server’s hostname fail, whereas requests to the

new virtual hostname are automatically redirected by Matrix Server to

a backup server.

Configure Servers for DNS Load Balancing

Matrix Server can provide failover protection for servers configured to

provide domain name service (DNS) load balancing. DNS load balancing

allows you to set up servers so that requests are sent alternately to each of

the servers in a matrix. For example, clients could access acmd1 and

acmd2 in turn, enabling the servers to share the load of accepting and

responding to client requests.

DNS includes a round-robin feature using address records (A records) to

alternate requests between IP addresses. This feature provides a

straightforward way to gain load balancing capability and simplified load

balancing, resulting in improved response time.

Matrix Server provides failover protection for this configuration. Without

Matrix Server, requests are simply alternated between the servers. If a

server goes down, requests to that server do not connect.

To configure for round-robin load balancing with Matrix Server, you

define virtual hosts as addresses in the A records on the DNS. Then use

Matrix Server to associate primary and backup servers with that virtual

host. In essence, you use the virtual host capability of Matrix Server to

accept the round-robin requests sent by the DNS. Matrix Server handles

the failover function to the real servers in the matrix.

Following is a simple example to demonstrate this capability. (The

example may not be applicable to your specific usage environment.) In