The way that a cluster fails over from one unit to the next depends on the type of cluster. Here is how the failover works in each type of cluster:
- Active/Active - The nodes in an Active/Active cluster don't do any automatic failover or load-balancing, so the failover operation is done by the load balancer. The nodes in the cluster host an HTML page that gives the status of all the nodes in the cluster.
The HTML page is located at the following URL: https://<IP address/hostname>/dana-na/healthcheck/healthcheck.cgi.
The external load balancer needs to be configured to send the following request to cluster nodes:
GET /dana-na/healthcheck/healthcheck.cgi HTTP/1.1\nHost: localhost. The node will return one of two values: 'Security gateway is accessible' or 500. 'Security gateway is accessible' means that the node is active; 500 indicates the PCS device is having problems and will not be able to handle user requests.
- Active/Passive - The nodes in an Active/Passive cluster are accessed via a Virtual IP address (VIP) that is "owned" by one of the two nodes in the cluster. The active node is the node that owns the VIP, and the passive node is the other node in the cluster. When a failover occurs, the VIP is transferred from the active node to the passive node and the passive node then becomes the active node and starts handling user requests.