Using a load balancer with server groups
The load balancer acts like a NAT device that routes any TCP or UDP traffic. Since the AR System server uses an ONC-RPC implementation that is layered on top of TCP/IP, AR System server traffic can be load balanced. Server groups are independent of load balancing, but the concepts are complementary.
You can run multiple AR System servers in a cluster and distribute the load between them with a third-party load balancer. All of these instances work on the same database, so they are always in sync. This is a typical server group configuration. This clustered environment creates a highly scalable and highly available AR System installation.
The servers in a server group can be given different responsibilities (such as one handing approvals, another escalations, etc). The servers in the group are aware of each other, and if one of the servers fails, another can take over its responsibilities
When installing applications in a server group environment, install all of the software on each computer before setting up the server group. This is necessary because the installer creates required configuration file entries, creates all required folders, and puts all the binary files in place. After installing the software, add each server to the server group, and configure the load balancer to distribute load among these instances.
The example below uses a load balancer to direct traffic to a server group of three AR System servers. In the following figure, the uppermost AR System server has the primary ranking for the Administration and Escalation operations. The other two AR System servers can be used to back up these operations, when the uppermost server is not running.
Basic load-balancer configuration with multiple AR System servers
For more information, see Configuring a hardware load balancer with BMC Remedy AR System.
If the load balancer belongs to a different domain than the AR System servers, then the fully qualified domain name of the Server-Name alias will be wrong. In this case, the domain name parameter should be specified in the ar.cfg file for each AR System server using the domain of the load balancer.
When a firewall or a load balancer exists between clients and AR System servers, you must set the TCP "keep alive" value properly. The operating system of the host BMC Remedy AR System server maintains the keep-alive socket (not the client). Ensure that the keep-alive value on the firewall or load balancer is at least as long as or longer than the keep-alive value on the largest host server of all AR System servers connected to the firewall or load balancer.