Setting up a load balancing configuration

You can set up load balancing if you are using WebSphere Application Server with CM Server.
Most of the load balancing setup occurs on the server side. The example runs on port 9080 on backend CM servers. The Load Balancer forwards client requests to backend CM servers based on load distribution and session affiliation rules.
Note: The load balancer described in this topic is the Edge Component that is available as an installation option in the enterprise edition of WebSphere Application Server.
Prior to installing the Load Balancer software, configuration of the network is required.

Configure and verify loopback adapter

Prior to configuring the loopback adapter, the HTTP server software should be installed since the steps require the user to verify that the HTTP server system is functioning prior to setting up the loopback adapter. To configure the loopback adapter the adapter is added and the cluster address is assigned to it. Once completed, any HTTP request received by the HTTP server machine that specifies the cluster address will be looped back to the machine's own IP address and handled by the HTTP server. Verify the cluster IP address is not being used by another machine prior to starting the configuration.

Configuring load balancer software

After installing the Load Balancer software you can configure the load balancer to manage requests.
  1. Start the Load Balancer dispatcher process (Services->IBM Dispatcher->Start).
  2. Connect to Load Balancer administration console (Start->Programs->IBM WebSphere->Edge Components->Load Balancer->Load Balancer).
  3. Right click Dispatcher and select Start Configuration Wizard. Select Next.
  4. Click Create Configuration. Select Next.
  5. Enter Web cluster address then click Update Configuration and Continue.
  6. Enter port number. For HTTP non-SSL use port 80, for SSL select port 443 then click Update Configurations and Continue, Select Next.
  7. Add HTTP servers. Click Add a server and enter a CM Server and then click Add a server again to enter another CM server. When completed select Next.
  8. Click Update Configuration and Continue.
  9. Start an Advisor. Select Yes, then select Next.
  10. Select operating system and click View Loopback Instructions followed by selecting Next.
  11. After you see the Congratulations message, click Exit and then click Yes.

Verify configuration

  1. From the command line run ipconfig on the Load Balancer to display the configured HTTP servers.
  2. From the command line on another machine (not HTTP or Load Balancer) ping the cluster IP address. This will indicate that the Load Balancer responds to browser requests that specify the Web cluster address.
  3. Select Dispatcher > Load Balancer > Host:webcluster > Executor:webcluster address="" > Cluster:webcluster.domain.com > Port:80 followed by right clicking Port 80. Select Monitor provides a graphical panel that allows you to observe new connections and distribution of the load across the HTTP servers.

Setting up a load balancing configuration for CCRC

The same view storage is needed for all backend CM servers (so a client request can be served on a backend CM server where the CCRC view was not registered to). CCRC clients must use the cluster address (a URL that goes through the load balancer). This can be achieved by setting two MBean attributes on the CM server:
  • ccrcViewStorage (for example, /net/qsun230/var/tmp/ccweb)
  • ccrcUseViewHostPathForGlobalPath (for example, true)
The following is an example on Solaris where the ccrcViewStorage MBean attribute is set to "/net/qsun230/var/tmp/ccweb" and the ccrcUseViewHostPathForGlobalPath MBean attribute is set to "true", so the CCRC view's global path shows the full NFS path:
lsview -l st99_view
Tag: st99_view
  Global path: /net/qsun230/var/tmp/ccweb/st99/st99_view/.view.stg
  Server host: qngz201
  Region: atria_r_d_unix
  Active: NO
  View tag uuid:dd1abb7d.3bd011dd.90c5.00:01:84:ab:f3:74
View on host: qngz201
View server access path: /net/qsun230/var/tmp/ccweb/st99/st99_view/.view.stg
View owner: cmbuqest.rational.com/st99

The following figure shows the load balancing configuration. For example, if the load balancer has an external IP of 10.10.20.1, and the two backend servers have IPs of 10.10.20.2 and 10.10.20.3 then CCRC clients would connect to the following URL: http://10.10.20.1:9080/TeamWeb/services/Team

This example assumes that CM server is running on port 9080 on backend CM servers. The load balancer forwards client requests to backend CM servers based on load distribution and session affiliation rules.


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