Understanding high availability  Deploying components to a cluster

Chapter 7: Load Balancing, Failover, and Component Availability

Configuring load balancing

Configure load balancing in EAServer Manager. While the cluster is running, you can display the per-server load to test the load balancing configuration.

StepsConfiguring load balancing

  1. Select the Clusters folder.

  2. Select the cluster that you want to configure.

  3. Select File | Properties. The Cluster Properties window displays.

  4. Select the Load Balancing tab. Click the Dynamic Load Balancing Enabled check box.

  5. Complete the load balancing property sheet and click OK. Default values are provided but you may want to modify them depending on the capabilities of the servers in your cluster. Load balancing properties are described in Table 7-1.

Table 7-1: Load balancing properties

Property

Description

Comments

Dynamic Load Balancing Enabled

Enables configuration of the dynamic load balancing policies (Weighted or Adaptive).

Sample interval

The interval, in seconds, that each server collects its load metrics.

The default value is five seconds.

Broadcast interval

The interval, in minutes, that each server broadcasts its load metrics to the other servers in the cluster.

The default value is five minutes.

Calculate interval

The interval, in minutes, that the load collectors in the name servers calculate and generate a normalized load list (NLL) of all member servers.

The default value is ten minutes.

Refresh interval

The interval, in minutes, that each name server obtains the NLL from its local load collector.

All name servers have their own copies of the NLL. The refresh interval is equal to or greater than the calculate interval.

The default value is ten minutes.

Maximum weight

The maximum weight, used in a weighted load balancing policy, of any server.

The default maximum weight is five. The maximum value is ten.

Policy

From the drop-down list, select the load balancing policy for this cluster.

If you select a weighted policy, you must supply a weighted value for each server in the cluster.

Weights

This property is enabled if you selected a weighted policy. Supply a weighted value for each server in the cluster, not to exceed the maximum weight value.

See “Weighted policy” for more information.

StepsViewing the current per-server load

  1. Select the Clusters folder.

  2. Highlight the cluster you want to view.

  3. Select File | Display Cluster Load.

The load graph is a bar chart. The load of each server is expressed as a percentage. Load is defined as the ratio of the number of bytes sent in the last 1/2 second over 10,000, expressed as a percentage.

The status list contains an entry for each server and tells whether the server is in Ready or Admin mode. If a server is in Admin mode, the list tells why.





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