Setting up clusters of servers
To configure a cluster of servers, set up a shared database and file system for the servers to use.
Before you begin
- Each server in the cluster must run the same version of HCL Launch.
- Ensure that each server can connect to each other
server on the network. For example, ensure that your firewall rules allow the servers to
communicate over HTTPS and JMS. Note: If you are using the Server-Agent, Authorized license mode, you will need a HCL Launch server license for each Cluster member. See, HCL license scenarios.
About this task
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; users are unaware of the multiple servers.
To ensure high availability of the JMS traffic, configure agents and agent relays for failover as described in Configuring agents for failover and Configuring agent relays for failover. In addition, you can also use DNS-level redirection to allow multiple servers or relays to act as a cluster for redundancy.
Procedure
- Set up a shared database for the servers to use.
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Set up network storage for the server configuration files.
Because each cluster server must access the same configuration files, each server must have access to this network storage.
- Configure online and offline backups for the servers.
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Install a load balancer to send requests to the servers.
The load balancer must be able to forward requests to the HTTP and HTTPS ports for the servers. For more information, see the documentation for your load balancer.Note: Do not configure a load balancer to distribute requests for the agent communication JMS port. To ensure agent and agent relay availability, configure them for failover.Important: You must configure the load balancer for session persistence, also known as session affinity.
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If you have one or more servers already installed, populate the network storage with
configuration files for the servers:
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If you terminate SSL at the server level, set the servers to use the same security
certificate.
For example, you can copy the certificate in the /opt/tomcat/conf/tomcat.keystore file to the other servers. Edit the tomcat.key.alias property in installed.properties file to specify the alias in the keystore that contains the certificate to use.
tomcat.key.alias=alias_of_your_certificate_in_tomcat_keystore
- Optional:
Configure the license server for high availability.
For information, see the Rational® Common Licensing documentation: http://www-01.ibm.com/support/knowledgecenter/SSSTWP. For high availability options for the license server, see http://www-01.ibm.com/support/docview.wss?uid=swg27036356&aid=1.
Results
Several server processes behave differently than with individual servers. See High-availability server processes.
What to do next
- Add servers to the cluster. See Adding servers to clusters.
- Set up cold standby servers to use for disaster recovery. See Adding cold standby servers.
- Configure agents and agent relays for failover. See Configuring agents for failover and Configuring agent relays for failover.