Load feedback resources

With load feedback, load balancing is controlled by measurements of entities called resources, which you define. A resource is the name for something that you can measure that is consumed by load on a data center and that reflects how you want to balance load across your data centers.

As an example, for a database application, you might decide that the most important load measurement is queries per second. You report the load in whatever units make sense to you. GTM considers loads as relative unit-less quantities.

You can configure a resource to constrain one property, or all properties for a data center if you are using XML load objects.

It is critical that resource load information is generated in real time and scales in response to traffic. When GTM directs traffic to a data center for a given property, it expects to see the load value increase. If the load value fails to increase, GTM continues to send traffic to the data center.

Akamai recommends the following load feedback resources:
  • The number of incoming HTTP/HTTPS/TCP connections
  • The state of a database pool

The sole factor influencing the resource must be the traffic directed to the data center by GTM for the constrained property/properties.

If end users access the server using a method other than via the property/properties constrained by the resource, the feedback mechanism cannot accurately manage the load. Other methods might include accessing the server directly, using other load feedback or non-load feedback properties across multiple domains, or using other load balancing technologies.

Akamai recommends that you avoid using the following feedback resources:
  • CPU load
  • Memory utilization
  • Bandwidth throughput data

Other local applications, automatic updates, database maintenance, or intensive cron jobs can all affect these values.