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Using Verastream Host Integrator with a Third-Party Load Balancer
Technical Note 10059
Last Reviewed 26-Oct-2006
Applies To
Verastream Host Integrator version 5.5 or higher
Summary
Technical Note 10059
Last Reviewed 26-Oct-2006
Applies To
Verastream Host Integrator version 5.5 or higher
Summary
This technical note explains how to configure Verastream Host Integrator for use with an external load balancer, instead of the Verastream built-in Session Server load balancing.
Comparing Verastream vs. Third-Party Load Balancing
Load balancers distribute client requests across multiple servers. When choosing a load-balancing solution appropriate for your environment, consider the following:
- Verastream built-in Session Server load balancing measures "load" based on the quantity of concurrent sessions in use by clients, as a percent of a configured maximum. This feature requires no additional hardware or software products. However, all Session Servers must be part of the same environment (sharing an AADS server or AADS failover environment). For more information on configuring Verastream built-in Session Server load balancing, see Technical Note 10052.
- An external third-party load balancer (such as F5 or Cisco products) can measure other factors, such as CPU utilization, or distribute clients in a pure round-robin or pseudorandom fashion. This option may be desired if your organization already uses a third-party load-balancing product to fulfill monitoring and reporting functions.
Note: This information has been successfully applied in customer environments. However, Attachmate does not officially endorse any third-party load balancer, nor perform regular interoperability testing.
Configuring your Verastream Environment
To set up Verastream to use an external third-party load balancer:
- Install Verastream software, including AADS and Session Servers.
Note: Do not configure any domains in the Verastream Administrative WebStation. Domains are used only for Verastream built-in load balancing.
- Configure your load balancer and/or DNS to create a new common host name or IP address that will be load balanced.
- If using a common host name, the new name should be different than the names entered when installing the Verastream software.
- If using a common IP address, the new address should be different than the actual IP addresses of the Verastream servers.
- Configure your external load balancer to monitor the health of Verastream Session Server services and systems (at a periodic interval) using one or more of the following approaches:
- ICMP Ping to verify the system is reachable.
- Script that connects and disconnects with Session Servers using the Verastream connector API (Java, .NET, COM, C, etc.).
- The atping utility on UNIX (as described in Technical Note 10054) to verify the Session Server service is running and reachable.
- Portscan-type connection to the Session Server TCP port 9623 that opens and closes to verify the service is running and reachable.
Note: Do not send any data on the Verastream service connection. Session Server uses a proprietary binary communication and does not support any text command interface.
- When deploying models (such as using activatemodel and deactivatemodel commands), use the specific Session Server system names (not the load balanced common name or address created in step 2 above).
- Since Verastream domains are not being used, your client code should use the ConnectToModel() or ConnectToSession() connector API method calls. For the server parameter, specify the load balanced name or address created in step 2 above.
Note: The suspendConnection() and resumeConnection() methods are not supported when using a third-party load balancing technology. Use of these methods in such environments may produce undesired results, such as the inability to resume suspended sessions.
