eG Monitoring
 

Measures reported by CtxNsGslbVsTest

A GSLB virtual server has one or more GSLB services bound to it, and load balances traffic among those services. It evaluates the configured GSLB methods (algorithms) to select the appropriate service to which to send a client request. Because the GSLB services can represent either local or remote servers, selecting the optimal GSLB service for a request has the effect of selecting the data center that should serve the client request.

The domain for which global server load balancing is configured must be bound to the GSLB virtual server, because one or more services bound to the virtual server will serve requests made for that domain. Unlike other virtual servers configured on a NetScaler appliance, a GSLB virtual server does not have its own virtual IP address (VIP).

To promptly detect irregularities in load-balancing and accurately point to the bottleneck points, you need to track requests to the sites, services, and virtual servers (that are bound to the services) and observe how every entity handles these requests. Using this test, you can figure out how the virtual servers load-balance the requests, responses, and data they receive. In the process, you can quickly identify overloaded virtual servers, and thus detect load-balancing irregularities.

The measures made by this test are as follows:

Measurement Description Measurement Unit Interpretation
Server_state Indicates the current state of this virtual server.   If the virtual server is up, then the value of this measure is Up. If the virtual server is down, then the value of this measure is Down.

The numeric values that correspond to these measure values have been listed in the table below:

Measure Value Numeric Value
Up 0
Down 1
Out of service 2
Transition out of service 3
Down when going out of service 4
Unknown -1

Note:

By default, this measure reports the above-mentioned Measure Values while indicating whether a virtual server is up/down. However, in the graph of this measure, the Measure Values will be represented using their corresponding numeric equivalents only.

You can use the detailed diagnosis of this measure to determine the protocol type of each virtual server being monitored.

Vserver_health Indicates the current health of this virtual server. Percent While a high percentage is indicative of good health, a low percentage indicates otherwise.
Client_cons Indicates the number of current client connections to this virtual server. Number These are good measures of the connection load on a virtual server. By comparing the value of each of these measures across servers, you can instantly identify overloaded servers and promptly detect irregularities in load-balancing.
Server_cons Indicates the number of connections to the actual servers behind this virtual server. Number
Client_cons_est Indicates the number of client connections to this virtual server that are currently in an ESTABLISHED state. Number
Server_cons_est Indicates the number of connections to the actual server behind this virtual server that are currently in an ESTABLISHED state. Number
Req_data_received Indicates the amount of request data received by this virtual server during the last measurement period. MB These are good measures of the request and response load on a virtual server. By comparing the value of each of these measures across virtual servers, you can instantly identify overloaded servers and promptly detect irregularities in load-balancing.

In the event that such irregularities come to light, you may want to consider fine-tuning the GSLB policies and/or GSLB methods and/or metric exchange policies supported by the system to ensure that the appliance takes intelligent load-balancing decisions.
Res_data_received Indicates the number of requests received by this virtual server during the last measurement period. MB
Req_received Indicates the number of requests received by the virtual server bound to this GSLB service during the last measurement period. Number
Res_received Indicates the number of responses received by this virtual server during the last measurement period. Number
Vserver_hits Indicates the number of times this virtual server has serviced a requrest during the last measurement period. Number If the value of this measure is equal to the number of requests received by this virtual server, then it indicates the virtual server was very busy during the last measurement period. On the contrary, if the value of this measure is less than the number of requests received by this virtual server, it could indicate that the virtual server was well-loaded.
Spill_threshold Indicates the spillover threshold that was set on this virtual server during the last measurement period. Number Spillover is a means to divert new connections from this virtual server to a backup vserver when the number of connections to this virtual server exceeds the threshold value. Spillover can either be connection-based or dynamic.
No_of_times_spillover Indicates the number of times the spill over threshold was exceeded by this virtual server during the last measurement period. Number A connection overload can cause a spillover. A high value of this measure indicates that the virtual server was often overloaded with connections. This can in turn be caused by inefficient load-balancing by the virtual server.