Specifications

Chapter 7: Monitoring Equalizer Operation
110 Equalizer Installation and Administration Guide
• Computed Load is a measure of the performance of the server relative to the overall
performance of the cluster. Equalizer tries to normalize the cluster-wide computed load value
to 100. If the server’s computed load value is above 100, it is performing below the overall
cluster performance.
Equalizer derives a server’s computed load value from its service time, number of active
connections, and server agent value (if configured). It is also takes into account the load
balancing policy used by the cluster.
Ideally, a server’s computed load should be around 100, though values in the range 85 to 115
are reasonable. If the server’s computed load is higher than 115, the server is not performing
well and you may need to add servers or upgrade to better servers. If you are using adaptive
load balancing, Equalizer lowers the server’s dynamic weight to reduce the number of
connections sent to that server. If the server’s computed load value is less than 85, the server
is performing very well and Equalizer will attempt to improve cluster-wide performance by
increasing the server’s dynamic weight to direct more traffic to it. Such adjustments to the
server’s weight will in turn affect its computed load value.
• Dynamic Weight is the percentage of incoming traffic that Equalizer dispatches to this server.
For example, if the cluster has three servers with dynamic weights of 100, 80, and 120, the
first server will get 100/(100+80+120) or 33.3% of the incoming traffic.
If a server is down, its dynamic weight is zero. If a server crashes and reboots, the period that
the server was down shows up as a gap in the dynamic weight plot.
If you are not using adaptive load balancing (for example, the load balancing policy is set to
round robin or static weight), Equalizer does not use dynamic weights. For more information
about setting the load balancing policy and adaptive load balancing, refer to “Configuring a
Cluster’s Load-Balancing Options” on page 74.
• Server Agent is the value that the server agent daemon returns. When queried, the server
agent returns a value in the range -1 to 100. If you have not configured the cluster to use the
server agent or the server agent daemon is not running on this server, the server agent value
defaults to 50 (that is, a value of 50 is used by the load balancing algorithm).
Server agent values above 60 to 70 indicate that the server is overloaded. If this persists and
you have enabled adaptive load balancing, Equalizer responds by reducing the server’s
dynamic weight so that fewer requests are routed to the server.
Displaying Geographic Cluster Parameters
If you have installed Envoy for your Equalizer, you can view information about each of the
geographic clusters that you have configured. For more information about Envoy, refer to Chapter
8, “Administering Geographic Clusters” on page 149.
To view the cluster-wide parameters, follow these steps:
Note – If all your servers have server agent values above 70, you probably have more traffic
than your servers can handle efficiently. In this case, Equalizer can help by intelligently managing
the overload, but the long-term solution is to upgrade the servers or add new ones.