Managing traffic with server weights

Weights are applied to all servers on a port. For any particular port, the requests are distributed between servers based on their weights relative to each other. For example, if one server is set to a weight of 10, and the other to 5, the server set to 10 should get twice as many requests as the server set to 5.

About this task

Weights are set by the manager function based upon internal counters in the executor, feedback from the advisors, and feedback from a system-monitoring program, such as Metric Server. If you want to set weights manually while running the manager, specify the fixedweight option on the dscontrol server command. For a description of the fixedweight option, see dscontrol manager.

The maximum weight boundary affects how much difference there can be between the number of requests each server will get. If you set the maximum weightbound to 1, then all the servers can have a weight of 1, 0 if quiesced, or -1 if marked down. As you increase this number, the difference in how servers can be weighted is increased. At a maximum weightbound of 2, one server could get twice as many requests as another. At a maximum weightbound of 10, one server could get 10 times as many requests as another. The default maximum weightbound is 20.

If an advisor finds that a server has gone down, it tells the manager, which sets the weight for the server to zero. As a result, the executor will not send any additional connections to that server as long as that weight remains zero. If there were any active connections to that server before the weight changed, they will be left to complete normally.

If all the servers are down, the manager sets the weights to half the weightbound.

Procedure

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Last updated: April 16, 2014 11:59 AM EDT
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