Application Delivery (ADX)

Occasional Contributor
Posts: 5
Registered: ‎03-09-2011

how can i verify dynamic weighted predictor


I setted one of our virtual servers' predictor as dynamic weighted

Regarding to configguide:

ServerIronADX(config-rs-rs1)# snmp-request oid 1

ServerIronADX(config-rs-rs1)#snmp-request community public

ServerIronADX(config)# server snmp-poll 5

ServerIronADX(config-vs-vs1)# predictor dynamic-weighted direct oid 1

I made similar configuration on our ADX for two real servers. Both of the servers are active and i can verify that Virtual server's predictor method is Dynamic Weighted R.R(show server real). But client requests are directed only one real server. Second one gets nothing. So we tried to verify how ADX use the collected data from servers.

When we run show server real command we see Weight: 1/1 for both of the real servers. But we could find no other clue about weights of servers. About how ADX use information those are collected from real servers.

Is there any other way to verify and trobleshoot for dynamic W.R.R?

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: how can i verify dynamic weighted predictor

Hope this helps.  Double read the last paragraph.

Dynamic-weighted Direct

The SNMP response from each server is regarded as a performance weight. The displayed SNMP Weight under “show server real” is the direct weight from the SNMP response. Weighted load balancing is similar to least connections, except that servers with a higher weight value receive a larger percentage of connections at a time. The dynamic weight is polled for the specified real server, and that weight determines the percentage of the current connections that are given to the server. The default weight is 0 if it does not receive any SNMP response. For example, in a configuration with five servers of various weights, the percentage of connections is calculated as follows:

Weight server1 = 7

Weight server2 = 8

Weight server3 = 2

Weight server4 = 2

Weight server5 = 5

Total weight of all servers = 24

The result is that server1 gets 7/24 of the current number of connections, server2 gets 8/24, server3 gets 2/24, and so on. If a new server, server6, is added with a weight of 10, the new server gets 10/34.

If the SNMP-weight indicates that your fastest server gets 50 percent of the connections, the server will get 50 percent of the connections at a given time. However, because the server is faster than others, it can complete more than 50 percent of the total connections overall by servicing the

connections at a higher rate. As a result, the weight is not a fixed ratio but instead adjusts to server capacity over time.

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