It is important for businesses to ensure continuous access to their virtualized infrastructure.
Citrix StoreFront is the first user-facing layer in the Citrix technology stack. It serves as an access point to the XenApp and XenDesktop resource repository and is vital to the XenApp and XenDesktop users for authentication and to launch their resources.
The StoreFront server relies on the Delivery Controllers to enumerate the published resources of the Site. If the connection to a Delivery Controller fails, the resources don’t show up in StoreFront and users can’t launch any apps or desktops. Ensuring the connectivity between StoreFront and the Delivery Controllers is therefore essential for the virtualization delivery team.
You can configure multiple Delivery Controllers within StoreFront to ensure high availability. This way, if one Delivery Controller is unavailable, others seamlessly take over resource provisioning.
Citrix SCOM Management Pack for StoreFront monitors the Delivery Controller availability through a data collection service (Citrix SCOM Management Pack for StoreFront Agent) that runs on the StoreFront servers. It probes, verifies, and reports on the availability of every configured Delivery Controller from the StoreFront’s perspective. SCOM administrators can detect and fix unavailable Delivery Controllers before users are affected.
As per the StoreFront planning guide, Citrix recommends that you configure environments that have several thousand users with NetScaler devices to load balance the XML requests sent from the StoreFront servers to the Delivery Controllers. This ensures an even load distribution among the Delivery Controllers and prevents potential bottlenecks.
In this deployment scenario, the Virtual IP address of the NetScaler load-balanced group masks the availability of the Delivery Controller as seen by StoreFront. As a result, StoreFront Management Pack probe cannot check the connection to the individual Delivery Controllers. The probe sees the entire load-balanced group as a single Delivery Controller (due to its Virtual IP), and triggers an alert only if all Delivery Controllers in the group become inaccessible.
To overcome this situation, you can use the monitoring capabilities offered by NetScaler for configured virtual services. You can set up the built-in monitors of NetScaler to check the StoreFront – Delivery Controller availability for the configured load balancing service.
For this scenario, the NetScaler appliance features two relevant built-in monitor types:
- The CITRIX-XD-DDC monitors the XenDesktop Delivery Controllers and
- The CITRIX-XML-SERVICE monitors XenApp’s XML Broker Services.
For steps to configure monitors for Delivery Controllers and the XML Broker Services on NetScaler, see Configuring Monitors in a Load Balancing Setup.
Bringing the monitoring cycle back into SCOM, Citrix Platinum licensed customers can take advantage of the “Load Balancing Service – State Monitor” from the Citrix SCOM Management Pack for NetScaler. This way, availability of each load-balanced Delivery Controller is made transparent for monitoring through Operations Manager.
Citrix SCOM Management Pack for NetScaler features a data collection service (Citrix SCOM Management Pack for NetScaler Agent). This service runs from the SCOM Management Group servers and probes the NetScaler devices through the Nitro API. Thus, it can read monitor states for load-balanced services.
On the SCOM side, the NetScaler MP’s “Load Balancing Service – State Monitor” is enabled by default, and triggers an alert when a configured Delivery Controller used in StoreFront is not available.
An appropriate alert appears in the NetScaler Active Alerts view in the Operations Manager console and the topology of the corresponding service reflects the unhealthy state.
Citrix customers with existing or new XenApp and XenDesktop Platinum licenses can take full advantage of the Citrix SCOM Management Packs’ monitoring capabilities, not only for XenApp and XenDesktop and StoreFront, but also for other Citrix virtualization and networking products. With a Platinum license, several additional benefits – apart from the Citrix SCOM Management Packs – are available to you as well. If you are not yet a XenApp and XenDesktop Platinum customer, be sure to check out the features.
Load balancing of Delivery Controllers through NetScaler hides the individual brokers from the StoreFront SCOM management pack probes. Built-in monitors of NetScaler can be set up to check the availability of individual Delivery Controllers at the load balancing service level. Citrix SCOM Management Pack for NetScaler can fetch alerts from load balancing services of NetScaler, making individual Delivery Controllers transparent for monitoring through SCOM again.
You can take advantage by combining Citrix SCOM Management Packs to gain a better insight into the Citrix infrastructure and to overcome monitoring challenges. This article explains how Citrix SCOM Management Pack for NetScaler complements the StoreFront management when NetScaler is used to load balance the XenApp and XenDesktop Delivery Controllers.
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