Coyote Point Systems Equalizer Especificações descarregar pdf (Página 230)

Server Pools and Server Instances

Managing Server Pools

A server is attached to a cluster via a server pool. A server pool is a collection of server definitions, each of which

has additional parameters assigned to it in the server pool -- these additional parameters are organized by the

server’s name and are referred to as server instances within the server pool context. This allows you to associated

a distinct set of server instance options (weight, flags, maximum number of connections), to multiple instances of

the same real server in different server pools.

The following subsections describe Server Pool management using both the GUI and CLI.

Configuring Server Pool Load-Balancing Options

Configure load balancing policy and response settings for each server pool 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 server pool.

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 performance.

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 server pool:

l Round-robin load balancing - distributes requests equally on the server pool in the cluster. Equalizer

dispatches the first incoming request to the first server, the second to the second server, and so on. When

Equalizer reaches the last server, it repeats the cycle. If a server in the cluster is down, Equalizer does not

send requests to that server. This is the default method.

The round robin method does not support Equalizer’s adaptive load balancing feature; so, Equalizer ignores

the servers’ initial weights and does not attempt to dynamically adjust server weights based on server

performance.

l Static load balancing - distributes requests among the servers depending on their assigned initial weights.

A server with a higher initial weight gets a higher percentage of the incoming requests. Think of this method

as a

weighted round robin

implementation. Static weight load balancing does not support Equalizer’s

adaptive load balancing feature; Equalizer does not dynamically adjust server weights based on server

performance.

Adaptive load balancing - distributes the load according to the following performance

indicators for each server.

Server response time is the length of time for the server to begin sending reply packets after

Equalizer sends a request.

Active connection count shows the number of connections currently active on the server.

Server agent value is the value returned by the server agent daemon (if any) running on the

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Coyote Point Systems Equalizer Especificações Página 230