Converged Load Balancer Deployments

You can configure your load balancer in different ways, depending on your goals and environment, as described in the following sections:

• Using Self-Load-Balancing Clusters

• Using Dedicated Load Balancing Server Instances

Using Self-Load-Balancing Clusters

In a development or production environment, you can designate that all server instances in a cluster participate in both redirecting and servicing requests, without using any dedicated load balancing instances. This is a self-load-balancing cluster, in which the target and the LB target are the same cluster.

A front-end hardware IP sprayer distributes request evenly across all instances in the cluster. If you do not use a hardware IP sprayer, a request can be forwarded to any server instance in the cluster. The converged load balancer component on that instance ensures that requests are distributed across the cluster. However, that instance is a single point of failure. The presence of a hardware IP sprayer ensures high availability.

Using Dedicated Load Balancing Server Instances

In a development environment, you can designate one or more stand-alone server instances as dedicated load balancers, which redirect requests to clusters or to other stand-alone instances that service those requests. These dedicated load balancers are called the targets of the load balancer.

The clusters or instances that service requests are called the LB targets of the load balancer. The LB targets of a specific load balancer can be clusters or stand-alone instances, but not a mixture of clusters and instances.

• Using Clustered Server Instances as LB Targets — The most common way to deploy the load balancer is with a cluster or clusters of server instances as the LB target or LB targets. By default all the instances in a cluster have the same configuration and the same applications deployed to them. The load balancer distributes the workload between the server instances and requests fail over from an unhealthy instance to a healthy one. If you have multiple clusters, requests can be load balanced across clusters but are only failed over between the instances in a single cluster.

• Using Multiple Stand-Alone Instances as LB Targets — It is also possible to configure your load balancer to use multiple stand-alone instances as LB targets, and to load balance and failover requests between these LB targets. However, in this configuration, you must manually ensure that the stand-alone instances have homogenous environments and the same applications deployed to them. Because clusters automatically maintain a homogenous environment, for most situations it is better and easier to use clusters.

  All instances in a cluster must have similar view for each other's IP address. For example, consider a cluster with two instances, say instance1 and instance2. When instance1 looks up instance2's IP address, it gets a.b.c.d. When instance2 looks up its own IP address, it should also see a.b.c.d, which is the same IP viewed by instance1. Ensure that the hosts file on your machine is correctly set up.

Dedicated load balancers are not supported in a production environment.