Coyote Point Systems E350GX, Руководство по установке и администрированию

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Plotting Server Performance History
Equalizer Installation and Administration Guide 195
3. In the drop down box, use the
Ctrl
or
Shift
keys and the left mouse button to select one or more of the following
statistics to plot:
Active Connections
The number of active connections on the server. Equalizer
“smooths” the connection count using a sliding-window smoothing
algorithm before being plotted.
Service Time
The time it takes a server to start sending reply packets once it has
received a client request. This value is very small for servers that
are primarily serving static HTML pages—typically 100-200
milliseconds. If the server is serving many active pages (such as /
cgi-bin pages), this value will be much higher. The service time
increases when the server is under heavy load because client
requests are queued until the server can handle them. Initialized to
0 when the system boots. By design, when a server with a non-
zero service time transitions to having no active connections for
some period of time, Equalizer stops adjusting the service time and
continues using the last service time value in load balancing
decisions. This is why sometimes the service time is not equal to 0
when there are no active connections to the server.
Computed Load
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
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 127.