Specifications

Chapter 6: Administering Virtual Clusters
90 Equalizer Installation and Administration Guide
For example, you might configure a server as a hot spare if you are using licensed software on
your servers and the license allows you to run the software only on one node at a time. In this
situation, you could configure the software on two servers in the cluster and then configure one
of those servers as a hot spare. Equalizer will use the second server only if the first goes down,
enabling you to make your application available without violating the licensing terms or having
to buy two software licenses.
11. Enable the quiesce check box to avoid sending new requests to the server. This is usually used
in preparation for shutting down an HTTP or HTTPS server. Please see “Shutting Down a
Server Gracefully” on page 92.
12. Enable the advanced flag if you want to set the dont probe check box; when set, dont probe
disables TCP health check probes for the server. This is usually used to disable probe checks
for a particular server without changing the probe settings for the server’s cluster.
13. Enable the advanced flag if you want to set the dont persist check box; when set, dont persist
disables persistence for the server when the persist flag (Layer 7 cluster) or a non-zero sticky
time (Layer 4 cluster) is set on the cluster. For a Layer 7 cluster, this means that no cookie will
be inserted into the response header on the way back to the client. For a Layer 4 cluster, no
sticky record is set. This flag is usually used to disable persistence for a hot spare. For an
example, see “Using a Hot Spare in a Cluster with a Maximum Connections Limit” on page 96.
14. Click the commit button.
Equalizer can refuse an Add Server command for several reasons, including:
• Attempting to add a server address that is already configured or is configured as a cluster
address
• Specifying an invalid IP address or port number
• Attempting to add more servers than are supported by Equalizer
Deleting a Server
To delete a server from a virtual cluster, follow these steps:
1. Log into the Equalizer Administration Interface in edit mode.
2. In the left frame, click the name of the server to be removed.
3. Select Delete Server from the local menu.
4. When prompted, click OK to confirm that you want to remove the server from the cluster.
If you attempt to delete a server with active connections, a confirmation dialog box appears. Click
Force to remove the server anyway. This action removes the server and deletes the active
connections and the user sessions they represent. To cancel the deletion, click Cancel.
Adjusting a Server’s Static Weight
Equalizer uses a server’s static weight as the starting point for determining the percentage of
requests to route to that server. Equalizer assigns servers with a higher static weight a higher
percentage of the load.
Values for server weights can be in the range 20-200 (and 0, which essentially disables the server).
When you install servers, set each server's static weight value in proportion to its “horsepower.” All
the static weights in a cluster do not need to add up to any particular number; it’s the ratio of the