Coyote Point Systems Equalizer, Руководство по установке и администрированию

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Working with Virtual Clusters
Equalizer Installation and Administration Guide 67
spread is 40%, a dynamic weight change from 100 to 105 will occur more quickly
than a change from 130 to 135 would.
The responsiveness settings correspond to the following weight spread
coefficients:
Slow : 10% (More time is required to change server dynamic weights.)
Medium : 7% (normal)
Fas t: 4% (Less time is required to change server dynamic weights.)
■
Optimization Threshold —controls how frequently Equalizer adjusts dynamic
weights. If Equalizer adjusts server weights very aggressively, oscillations in
server weights can occur and cluster-wide performance can suffer. If Equalizer
doesn’t adjust weights often enough, server overloads might not be compensated
for quickly enough and cluster-wide performance can suffer.
The responsiveness settings correspond to the following optimization threshold
values:
Slow : 10% (least aggressive optimization threshold)
Medium : 17.5%
Fast : 25% (most aggressive optimization threshold)
6. Click the Set button.
Aggressive Load Balancing
After fine-tuning the static weights of each server in the cluster, you might discover that
Equalizer is not adjusting the dynamic weights of the servers at all—the dynamic weights
are very stable, even under heavy load. In this case, you might want to set the cluster’s
load balancing responsiveness parameter to fast. This will cause Equalizer to try to
optimize the performance of your servers more aggressively and should improve the
overall cluster performance. For more information about setting server weights, see
“Adjusting a Server’s Static Weight” on page 76.
Dynamic Weight Oscillations
If you notice that there are oscillations in a particular server’s dynamic weight—the
dynamic weight is varying from far below 100 to far above 100 and back again—you might
benefit by choosing the slow responsiveness setting for the cluster. You should also
investigate why this is happening—it’s possible that the server application (httpd) is
behaving erratically.