When you do not enable the "Disable Primary When Down" option on an Active and Passive Global Server Load Balancing (GSLB) virtual servers on a NetScaler appliance, the "Disable Primary When Down" option is bypassed.

Ensure that you enable the Disable Primary When Down option on the primary GSLB virtual server in the production as well as the disaster recovery NetScaler appliances, as shown in the following screenshot:

Problem Cause

This is according to the design of the NetScaler software.

The Active-Passive configuration of the GSLB is a popular solution for organizations that have a production data center and a Disaster Recovery data center. With this configuration, the network traffic is only required to flow into the production data center under normal operations and then diverted to the Disaster Recovery data center, if there is a loss of service in production data center, such as when a web server is not available.

To ensure that network services are only transferred back to the production data center when all services are ready, you can enable the "Disable Primary When Down" option on the GSLB virtual servers that represent the production network services. When there is a loss of service or ability of the network users to access resources at the production location, the network traffic is diverted to the Disaster Recovery data center. If services are restored at the production data center, the network traffic remains diverted to the Disaster Recovery data center until an administrator can manually re-enable the GSLB virtual servers at the production data center.

This setup does not work as expected if you only enable the "Disable Primary When Down" option in the GSLB virtual servers of the production NetScaler appliances. If this option is not enabled in the GSLB virtual servers of the Disaster Recovery NetScaler appliances, you might observer the following sequence of incidents:

1. The back end web server that is mapped to the production GSLB service fails a monitor and the status of the GSLB virtual servers is marked as DOWN.

2. The network traffic is diverted to the backup virtual servers, which is the Disaster Recovery GSLB virtual servers in the Disaster Recovery NetScaler appliance.

3. The back end web server in the production data center is restored and monitors pass causing the production GSLB virtual servers to be available.

4. The "Disable Primary When Down" option is enabled on the production GSLB virtual servers. Therefore, this virtual server does not actively server traffic and continues to advertise the Disaster Recovery GSLB virtual server as the active virtual server.

If you do not enable the "Disable Primary When Down" option on the GSLB virtual servers in the Disaster Recovery data center NetScaler appliance and when the production GSLB virtual server is available, then the network traffic is sent to the production data center. This results in production as well as the Disaster Recovery data centers serving traffic at the same time, which is not desirable for an Active-Passive configuration.