Polling overview 编辑

Polling is a process, where Citrix Application Delivery Management (ADM) collects certain information from Citrix ADC instances. You might have configured multiple Citrix ADC instances for your organization, across the world. To monitor your instances through Citrix ADM, Citrix ADM has to collect certain information such as CPU usage, memory usage, SSL certificates, licensed features, license types, and so on from all managed ADC instances. The following are the different types of polling that occur between ADM and the managed instances:

• Instance polling

• Inventory polling

• Performance data collection

• Instance backup polling

• Configuration audit polling

• SSL certificate polling

• Entity polling

Citrix ADM uses protocols such as NITRO call, Secure Shell (SSH), and Secure Copy (SCP) to poll information from Citrix ADC instances.

How Citrix ADM polls managed instances and entities

Citrix ADM automatically polls at regular intervals by default. Citrix ADM also enables you to configure polling intervals for a few polling types and allows you to poll manually when required.

The following table describes the details of types of polling, polling interval, protocol used, and so on:

Note

In addition to polling, events generated by managed ADC instances are received by Citrix ADM through SNMP traps sent to the instances. For example, an event is generated when there is a system failure or change in configuration.

During instance backup, SSL files, CA certificate files, ADC templates, database information, and so on are downloaded to Citrix ADM. During a configuration audit, ns.conf files are downloaded and stored in the file system. All information collected from managed Citrix ADC instances are stored internally within the database.

Different ways of polling instances

The following are the different ways of polling that Citrix ADM performs on the managed instances:

• Global polling of instances

• Manual polling of instances

• Manual polling of entities

Global polling of instances

Citrix ADM automatically polls all the managed instances in the network depending on the interval configured by you. Though the default polling interval is 30 minutes, you can set the interval depending on your requirements by navigating to Networks > Network Functions > Settings.

Manual polling of instances

When Citrix ADM is managing many entities, the polling cycle takes a longer time to generate the report that might result in a blank screen or the system might still display earlier data.

In Citrix ADM, there is a minimum polling interval period when automatic polling does not happen. If you add a new Citrix ADC instance, or if an entity is updated, Citrix ADM does not recognize the new instance or the updates made to an entity until the next polling happens. And, there is no way to immediately get a list of virtual IP addresses for further operations. You must wait for the minimum polling interval period to elapse. Though you can do a manual poll to discover newly added instances, this leads to the entire NetScaler network to be polled, which creates a heavy load on the network. Instead of polling the entire network, Citrix ADM now allows you to poll only selected instances and entities at any given time.

Citrix ADM automatically polls managed instances to collect information at set times in a day. Selected polling reduces the refresh time that Citrix ADM requires to display the most recent status of the entities bound to these selected instances.

To poll specific instances in Citrix ADM:

1. In Citrix ADM, navigate to Networks > Network Functions.

2. On Network Functions page, at the top right-hand corner, click Poll Now.

3. The pop-up page Poll Now provides you an option to poll all Citrix ADC instances in the network or poll the selected instances.

   1. All Instances tab - click Start Polling to poll all the instances.

   2. Select Instances tab - select the instances from the list

4. Click Start Polling.

   

   

Citrix ADM initiates manual polling and adds all the entities.

Manual polling of entities

Citrix ADM also allows you to poll only a few selected entities that are bound to a particular instance. For example, you can use this option to know the latest status of a particular entity in an instance. In such a case, you need not poll the instance as a whole to know the status of one updated entity. When you select and poll an entity, NCitrix ADM polls only that entity and updates the status in the Citrix ADM GUI.

Consider an example of a virtual server being DOWN. The state of that virtual server might have changed to UP before the next automatic polling happens. To view the changed status of the virtual server, you might want to poll only that virtual server so that the correct state is displayed on the GUI immediately.

You can now poll the following entities for any update in their status: services, service groups, load balancing virtual servers, cache reduction virtual servers, content switching virtual servers, authentication virtual servers, VPN virtual servers, GSLB virtual servers, and application servers.

Note

If you poll a virtual server, only that virtual server is polled. The associated entities such as services, service groups, and servers are not polled. If you need to poll all associated entities, you must manually poll the entities or you must poll the instance.

To poll specific entities in Citrix ADM:

As an example, this task assists you to poll load balancing virtual servers. Similarly, you can poll other network function entities too.

1. In Citrix ADM, navigate to Networks > Network Functions > Load Balancing > Virtual Servers.

2. Select the virtual server that shows the state as DOWN, and click Poll Now. The status of the virtual server now changes to UP.