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.
Prior to installing the Load Balancer software, configuration of the network
is required.
- Make sure the Load Balancer and HTTP servers are on the same LAN segment.
- The Load Balancer requires a static IP address.
- Make sure Load Balancer can ping the HTTP servers.
- Obtain an IP address to be used as a cluster address by the Load Balancer.
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.
- Execute route print to verify.
- Verify that you can ping the HTTP servers.
- Verify that the HTTP server is functioning properly by starting the HTTP
server system and invoking the HTTP Server welcome page.
- Define the loopback adapter.
Configuring load balancer software
After installing the Load Balancer software you can configure the load
balancer to manage requests.
- Start the Load Balancer dispatcher process (Services->IBM Dispatcher->Start).
- Connect to Load Balancer administration console (Start->Programs->IBM
WebSphere->Edge Components->Load Balancer->Load Balancer).
- Right click Dispatcher and select Start Configuration Wizard.
Select Next.
- Click Create Configuration. Select Next.
- Enter Web cluster address then click Update Configuration and
Continue.
- Enter port number. For HTTP non-SSL use port 80, for SSL select port 443
then click Update Configurations and Continue, Select Next.
- 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.
- Click Update Configuration and Continue.
- Start an Advisor. Select Yes, then select Next.
- Select operating system and click View Loopback Instructions followed
by selecting Next.
- After you see the Congratulations message, click Exit and
then click Yes.
Verify configuration
- From the command line run ipconfig on the Load Balancer to display
the configured HTTP servers.
- 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.
- Select 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.