Virtual Service Test

On the Application Delivery Controller appliance, a virtual service (also referred to as a virtual server or virtual host) is configured by specifying a Virtual IP/Port and the protocol for the load balancing operations. The virtual server is bound to a number of real services (also called as real servers) within a server farm and associated with a number of groups. The virtual server is typically a publicly facing IP address which responds to user requests. Whenever the requests are received from users, the virtual server responds to those requests by channelizing the requests to the real servers. This way, the appliance will load balance the requests to different real services.

Since the virtual servers are able to manage the traffic and divert user requests to servers that are managing fewer requests, poor performance and outages can be avoided. Irregularities in load balancing can cause significant delay in request processing thus affecting the user experience with the target delivery controller. To avoid this, you can configure the periodic execution of the Virtual Services test.

For each virtual service (server) configured on the delivery controller, this test continuously monitors the load on the load-balancing virtual servers and reveals how well each server processes user requests. In addition, this test detects inconsistencies in load-balancing early on and warns administrators of possible deviations proactively.

Target of the test : An Array Application Delivery Controller

Agent deploying the test : A remote agent

Outputs of the test : One set of results for each virtual server on the target Array Application Delivery Controller that is to be monitored.

Configurable parameters for the test
Parameter Description

Test Period

How often should the test be executed.

Host

The IP address of the host that is being monitored.

SSH Username and
SSH Password

Specify the credentials of a user who has the right to execute CLI (command-line interface) commands on the target delivery controller and pull out metrics via SSH.

Confirm Password

Confirm the SSH Password by retyping it here.

SSH Port

Specify the SSH port of the target delivery controller here; The default value is 22.

SSH Enable Password

The delivery controller offers three levels or modes to the ArrayOS. The modes are given below:

  • User Mode - In this mode, user can perform the authorized and basic operations and non-critical functions.
  • Enable Mode - When this mode is selected, the user can run majority of commands for view data.
  • Config Mode - Using this level, the user can change the configuration of the delivery controller for global configuration and access (Using CLI commands).

The SSH Enable password is the password that is needed for the user to access the commands when the Enable Mode is selected.

Confirm Password

Confirm the SSH Enable Password by retyping it here.

Timeout

Specify the duration (in seconds) within which the SNMP query executed by this test should time out in this text box. The default is 10 seconds.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Number of groups associated

Indicates the number of groups associated with this virtual server.

Number

 

Number of real services associated

Indicates the number of real servers that are associated with this virtual server.

Number

 

Data transmitted

Indicates the amount of data that was transmitted from this virtual server during the last measurement period.

KB

Compare the values of these measures across virtual servers to identify the server that is handling maximum traffic.

Data received

Indicates the amount of data that was received by this virtual server during the last measurement period.

KB

Packets transmitted

Indicates the number of packets that were transmitted from this virtual server during the last measurement period.

Number

Compare the value of these measures across the real servers to identify the virtual server that is experiencing the maximum traffic.

Packets received

Indicates the number of packets that were received by this virtual server during the last measurement period.

Number

Maximum connection count

Indicates the maximum number of connections that are established on this real server.

Number

This measure is a good indicator of the load on the virtual server.

Current connection count

Indicates the number of connections that are currently active on this virtual server.

Number

 

Outstanding request count

Indicates the number of requests that are currently in an outstanding state on this virtual server.

Number

 

Hits

Indicates the number of requests received by this virtual server.

Number

A value close to 100% indicates that the real server is currently overloaded.