Configuring clustered servers for high availability

You can set up multiple servers for a clustered or high-availability configuration. In this configuration, multiple servers run at the same time.

Before you begin

Install a load balancer. This load balancer will distribute requests to the servers in the cluster.

About this task

To set up servers in a clustered configuration, you install the server on separate systems and connect the servers to the same database. Then, you configure a load balancer to distribute the traffic between the servers. Instead of accessing the servers directly, users access the load balancer URL. To the users, that URL appears to host a single instance of the server with high capacity; the users are not aware of the multiple servers.

Procedure

Install and configure the database as usual. If you already have a database, you can use it for the clustered servers. See Installing the database.
If you already have one or more servers, convert them to cluster servers with the following steps:
1. Stop the server.
2. On the server, open the file install_folder/ucrelease/conf/server.properties in a text editor. Use the server installation directory for install_folder.
3. In this file, update the public.url parameter to the URL and port of the load balancer. Escape colons and other special characters with a backslash (\), as in the following example:
```
public.url=http\://balancer.example.com\:8080
```
4. Save the file.
To install new cluster servers, install the servers as usual, but with the following changes:
- Connect each server to the same database.
- For the host name that the users access, specify the host name of the load balancer, not the computer that hosts the server.
- If you are installing the server on the same computer as another server, use a different port for HTTPS requests for each server.
See Installing the server. Be sure to note the ports for each server because you will need this information later. The default port for HTTP requests is 8080 and the default port for HTTPS requests is 8443.
Start each server.
Log in to one server and select the Keep me logged in check box.
Open the server.properties file for that server.
In the server.properties file, find the property cookie.key and copy it. This property specifies a key that is included in a cookie when a user logs in. Later, you will copy this key to the other servers so users do not need to sign in separately on each server.
In the server.properties file for each server, add the following properties:
```
ha.activation.enabled=yes
ha.node.name=nodeName
cookie.key=cookieKey
```
For nodeName, specify a unique node name for each server. After you have set up the servers, this node name appears on each server. Knowing which server you are using can help you debug problems. To see the name of the node that you are using, click Help at the top of any page. The node name is shown in the menu, as shown in the following figure:
For cookieKey, specify the cookie key that you copied from the first server. This key must be the same on each server.
For example, the code that you add to the server.properties file might look like the following example:
```
ha.activation.enabled=yes
ha.node.name=HA node 1
cookie.key=D3ZizBbRSWFjdOQ8N2a/yQ\=\=
```
Optional: To store attachments on a shared directory, add the property attachments.folder.path and specify the shared directory, as in the following example:
```
attachments.folder.path=/
```
Restart each server.
Configure a load balancer to share the load between the servers. For more information, see the documentation for your load balancer.

Results

After you configure the load balancer to distribute connections to the servers, users can connect to a single URL and use the capacity of all of the servers. The servers also ensure that only one license per user is used, even if a user accesses multiple servers.

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