This documentation supports the 21.05 version of Action Request System.
To view an earlier version, select the version from the Product version menu.

Configuring load balancers between the mid tier and a server group

To configure the load balancer between Mid Tier servers and the AR System server without a "sticky bit," click the Connection Settings link in the left navigation pane to open the Connection Settings page.

Best Practice

We recommend that you configure a load balancer between Mid Tier servers and the AR System server without using a "sticky bit" (session affinity).

If your system uses a hardware load balancer between Mid Tier and AR System servers, make sure the Enable Lifespan check box is selected on the Connection Settings page. This configuration allows sessions from any mid tier server to be distributed to any AR System server on the fly, and enables the system to rebalance in a timely manner if a server is added to or removed from the system. This top group of settings facilitates load rebalancing within a server group. 

The settings on the Connection Settings page enable you to limit the number of proxy connections and specify how long proxy connections can stay open. Whether the Connection Lifespan or Connection Timeout setting is met first determines the number of current idle connections, which is displayed in the Idle column in the Connection Pool Status area.

Mid Tier Configuration Tool - Connection Settings page


The following table describes each of the parameters:

SettingDescription

Settings to support Load Balancers between Mid Tier and Server group without sticky bit (session affinity)

Enable Lifespan

Specifies whether to enable the rebalancing of connection loads between Mid Tier group and the server group. If the check box is:

  • Selected—Any connection session open longer than the Connection Lifespan parameter value will be reopened with a rebalanced load within the server group.
  • Cleared—Load balancing will not be enabled.
Connection Lifespan (Minutes)

The amount of time (in minutes) that a connection will be load balanced after it is created. To prevent any load balancing on the connection, keep this parameter at its default value of 0. Whether the Connection Lifespan or Connection Timeout setting is met first determines the number of current idle connections.

Recommended value: 15 minutes

Balance Now

Sets the Connection Lifespan to 5 minutes, temporarily for a 10 minute period, to quickly rebalance the connection loads between Mid Tier group and the server group. If a AR System server is down, the mid tier quickly routes connections to functional AR System servers. It also starts rebalancing existing not-in-use connections that had the original Connection Lifespan value.

When the 10 minute period concludes, the connections then go back to their configured Connection Lifespan value.

Connection Pool Settings

Maximum Connections per Server

The maximum number of proxy connections that a connection pool can contain per server. If the number of existing connections for the requested server does not exceed this value, a connection is allocated to that server. The default value is 80.

This setting is usually not changed from its default value, because it represents a pool of connections and not the number of users who can connect to a AR System server.

Connection Timeout (Minutes)

The amount of time (in minutes) that the pooled connections exceeding the Idle Connections per Server can be idle before being terminated. This time limit makes sure that active pools routinely clean up their excess idle connections. To prevent any idle pooled connections from terminating before the client shuts down, set this parameter to 0. Whether the Connection Lifespan or Connection Timeout setting is met first determines the number of current idle connections.

Idle Connections per Server

The maximum number of idle connections per server that are not subject to the Connection Timeout. These connections are always available after they are established. The default value is 5. If the Idle Connections per Server is set to 0, then the connection pool will be closed when all connections are closed.

Connection Pool Status

Pool Name

The host name and port number for the server hosting the connection pool.

In Use

The number of pooled proxy connections in use.

Idle

The number of established connections that are available in the connection pool.

Max Available

The maximum number of pooled proxy connections for this pool.

High Water Mark

The largest reached pool size.

Last Used

The datetime stamp when the pool was last used.

Created

The datetime stamp when the pool was created.

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