Coyote Point Systems Equalizer, Installation And Administration Manual

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Chapter 5: Administering Virtual Clusters
76 Equalizer Installation and Administration Guide
4. Enter the following information:
5. Enable the Hot Spare checkbox if this server is to be used as a backup server in case
the other servers in the cluster fail. If Hot Spare is checked, Equalizer will only direct
incoming connections to this server if all of the other servers in the cluster are down.
Most servers will not be configured as hot spares.
For example, it might be useful to configure a server as a hot spare if you are using
licensed software on your servers and the license allows you to only run the software
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 the servers as a hot spare. Equalizer
will only use the second server if the first goes down, enabling you to achieve high
availability for your application without violating the licensing terms or having to buy
two software licenses.
6. Click the Add button.
An Add Server command can be refused 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
Adjusting a Server’s Static Weight
Equalizer uses a server’s static weight as the starting point for determining what
percentage of requests to route to that server. Equalizer assigns servers with a higher static
weight a higher percentage of the load. The relative values of server static weights are more
important than the actual values. For example, if you have two servers in a cluster and one
has roughly twice the “horsepower” of the other, setting the static weights to 50 and 100 is
equivalent to setting the static weights to 100 and 200.
If Equalizer is performing adaptive load balancing (ALB), you should generally use higher
static weights. When Equalizer’s ALB feature is enabled (the load balancing policy is not
set to round robin or static weight), using higher static weights will produce finer-grained
load balancing. Higher weights enable Equalizer to adjust server weights more
Server Name The logical name for the server. Each server in a cluster must have a unique
name that begins with an alphabetical character, not a numeral. For example,
Phoenix.
Server Address The IP address of the server endpoint you are adding to the cluster.
Port The port number of the service on the server machine. Unless you want to set up
port redirection, the default value is usually correct. (The default is the same as
the port of the virtual cluster.)
Static Weight The static weight is used as a starting point for determining what percentage of
requests to route to each server. See “Adjusting a Server’s Static Weight” on page
76 for information about selecting an appropriate static weight.
Note – Equalizer performs all of the encryption and decryption for HTTPS clusters, so traffic
between the Equalizer and the servers in an HTTPS cluster uses the HTTP protocol. When you
add servers to an HTTPS cluster, you should configure them on port 80.