Specifications

Chapter 6: Administering Virtual Clusters
74 Equalizer Installation and Administration Guide
• certify_client applies to HTTPS clusters and indicates whether the server asks the client for a
client certificate when a client request is received. The connection will succeed even if the
client does not provide a certificate; but, if one is provided by the client it will be validated.
See Appendix D, ”HTTPS Cluster Certificates”.
• require certificate applies to HTTPS clusters and indicates whether the server requires a
client certificate when a client request is received. If the client does not provide a certificate,
the connection is refused. This flag takes precedence over the certify_client flag; i.e., if both
of these flags are specified, the client certificate is required. See Appendix D, ”HTTPS
Cluster Certificates”.
• verify once applies to HTTPS clusters and indicates that the server will verify certificates
only on the first client request, even if SSL is renegotiated. See Appendix D, ”HTTPS
Cluster Certificates”.
• ssl_unclean_shutdown applies to HTTPS clusters and should be checked if you see errors
(cannot see pages) while trying to maintain HTTPS persistent connections over HTTP/1.1.
This problem especially applies to connections between Internet Explorer and Apache Servers
and usually occurs intermittently.
Deleting a Virtual Cluster
You cannot delete a cluster with servers assigned to it. So, before attempting to delete the cluster,
delete all servers from the cluster. For information about removing servers from a cluster, refer to
“Deleting a Server” on page 90.
To delete a cluster, follow these steps:
1. Log into the Equalizer Administration Interface in edit mode.
2. In the left frame, click the name of the cluster to be deleted. The cluster’s parameters appear in
the right frame.
3. Select Delete Cluster from the local menu.
4. When prompted, click OK to confirm that you want to remove the cluster permanently.
Configuring a Cluster’s Load-Balancing Options
Configure load balancing policy and response settings for each cluster independently. Multiple
clusters do not need to use the same load balancing configuration even if the same physical server
machines host them. For example, if one cluster on port 80 handles HTML traffic and one on port
8000 serves images, you can configure different load balancing policies for each cluster.
When you use adaptive load balancing (that is, you have not set the cluster’s load balancing policy
to round robin or static weight), you can adjust Equalizer to optimize cluster performance. For more
information, see “Adjusting a Server’s Static Weight” on page 90.
Equalizer’s Load Balancing Policies
Equalizer supports the following load balancing policies, each of which is associated with a
particular algorithm that Equalizer uses to determine how to distribute requests among the servers in
the cluster:
• round robin load balancing distributes requests equally among all the servers in the cluster.
Equalizer dispatches the first incoming request to the first server, the second to the second