GSLB Services Test

A GSLB service is usually a representation of a load balancing or content switching virtual server, although it can represent any type of virtual server. The GSLB service identifies the virtual server’s IP address, port number, and service type. GSLB services are bound to GSLB virtual servers on the NetScaler appliances managing the GSLB sites.

A GSLB service bound to a GSLB virtual server in the same data center is local to the GSLB virtual server. A GSLB service bound to a GSLB virtual server in a different data center is remote from that GSLB virtual server. 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.

Using the GSLB Services test, you can monitor the request, response, and data load on the individual services configured on the NetScaler appliance, evaluate the efficiency with which the appliance distributes this load to the services, and promptly detect irregularities (if any) in load-balancing.

Target of the test : A NetScaler VPX/MPX

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each GSLB service.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The IP address of the host for which the test is being configured.

NetScaler Username and NetScaler Password

To monitor a NetScaler device, the eG agent should be configured with the credentials of a user with read-only privileges to the target NetScaler device. Specify the credentials of such a user in the NetScaler Username and NetScaler Password text boxes.

SSL

The eG agent collects performance metrics by invoking NITRO (NetScaler Interface Through Restful interfaces and Objects) APIs on the target NetScaler device. Typically, the NITRO APIs can be invoked through the HTTP or the HTTPS mode. By default, the eG agent invokes the NITRO APIs using the HTTPS mode. This is why, the SSL flag is set to Yes by default. If the target NetScaler device is not SSL-enabled, then the NITRO APIs can be accessed through the HTTP mode only. In this case, set the SSL flag to No.

Show Up Server Only

The default setting of this flag is No; this indicates that this test, by default, monitors all the GSLB services configured on the NetScaler appliance. If you want the test to monitor only those GSLB services that are up and running currently, then set this value to Yes.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test

Measurement

Description

Measurement Unit

Interpretation

Server state

Indicates the current state of the virtual server with which this service is bound.

 

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:

Numeric Value Measure Value
0

Up

1

Down

2

Out of service

3

Transition out of service

4

Down when going out of service

-1

Unknown

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.

The detailed diagnosis of this measure reports the service type, the primary IP address of the service, and its primary port.

Current load on the service

Indicates the load on the service that is calculated from the bound load based monitor.

Percent

In a load-balanced setup, the value of this measure should be low or should be more or less the same for all services. A very high value for this measure could indicate that the service is overloaded. You may then want to consider fine-tuning your GSLB policies and metric exchange policies to ensure that the load-balancing irregularities are removed. 

Current client connections

Indicates the number of current client connections to this service

Number

These are good measures of the connection load on a service. By comparing the value of each of these measures across services, you can instantly identify overloaded services and promptly detect irregularities in load-balancing.

Current server connections

Indicates the number of connections to the actual servers behind the virtual server that is bound to this service.

Number

Client connections in established state

Indicates the number of client connections to this service that are currently in an ESTABLISHED state.

Number

Server connections in established state

Indicates the number of connections to the actual server behind the virtual server that is bound to this service that are currently in an ESTABLISHED state.

Number

 

Request data received

Indicates the amount of request data received by the virtual server bound to this GSLB service during the last measurement period.

MB

These are good measures of the request and response load on a service. By comparing the value of each of these measures across services, you can instantly identify overloaded services 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.

Response data received

Indicates the amount of response data received by the virtual server bound to this GSLB service during the last measurement period.

MB

Requests received

Indicates the number of requests received by the virtual server bound to this GSLB service during the last measurement period.

Number

Responses received

Indicates the number of responses by the virtual server bound to this GSLB service during the last measurement period.

Number

Virtual server hits

Indicates the number of times this service has been provided during the last measurement period.

Number

If the value of this measure is equal to the number of requests received for this service, then it indicates that all requests have been fulfilled. On the contrary, if the value of this measure is less than the number of requests received, it could indicate that one/more requests could not be serviced. This is a cause for concern.