Citrix xenapp 6.5 prefered and most preferred

Citrix XenApp 6.5: Best Practices for Load Balancing and Failover

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Introduction

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In today's fast-paced IT environment, ensuring high availability of critical applications is crucial for business continuity. Citrix XenApp 6.5 plays a vital role in delivering desktops and applications to users across the globe. However, even with robust infrastructure design, failures can still occur due to hardware or software issues.

This article will delve into best practices for load balancing and failover within a XenApp 2-tier farm configuration using Citrix Presentation Server (now known as XenDesktop VDI), focusing on preferred versus most-preferred data collector settings. By following these guidelines, administrators can ensure minimal disruption when failures do occur.

Understanding Data Collectors

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In XenApp 6.x and later versions, a load-balancing mechanism called zone affinity is introduced to improve the performance of Citrix Receiver connections. Zone affinity ensures that client computers always connect to one or more servers within their designated zone based on various factors such as server name, IP address range, MAC address ranges, etc.

Within each zone, you can configure either one primary data collector (DC) with a preference set to 'Most Preferred' or multiple secondary DCs having a lower preference level of 'Preferred.' The purpose behind this design is twould allow Citrix Receiver clients to automatically fail over seamlessly in case the primary DC becomes unavailable due to hardware failure or software issues.

Configuring Data Collectors for High Availability

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To achieve high availability within your XenApp 6.5 farm, follow these steps:

1. Log into each server's Control Center interface.

2. Navigate through the 'Citrix XenDesktop' > 'Optimization' section and click on 'Edit Global properties'.

3. Scroll down to the bottom until you see a heading called “Advanced Settings'. Clicking this link will reveal several additional options; locate the following two settings:

- Set 'DC_PriorityMode' to 1 (Most Preferred)

- For multiple secondary DCs, set it to 2 and then specify each server's IP address separated by commas under “SecondaryDatacenters”.

4. Once done saving changes on all servers restart them one at every reboot time.

Citrix Receiver Client Configuration

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After completing the above steps on your XenApp farm side, you must now configure Citressor client machines to use these newly created data collectors:

1. Open up Start menu > Programs and double-click “Citrix Workspace” icon.

2. In next dialog box select 'Add/Remove' button located at bottom left corner of window then click Next until reached screen titled 'Connection'. Here uncheckmark both boxes labeled 'Use only my intranet (LAN)' checkbox followed with OK button press afterwards!

3. Now go back into Start menu > All Programs and double-click “Citrix Receiver” again; from newly opened dialog box select Tools tab near top left corner then click Options under Advanced heading where you'll see two radio buttons: 'Always use this server' vs 'Use next available published desktop'.

To force Citrix clients to always connect via a specific data collector:

1. Launch the Citrix Workspace app.

2. Navigate to Edit > Preferences...

3. Under User Experience, select the desired connection type (Citrix Receiver, Thinwire 3+, etc.)

4. In the right-hand pane, under Advanced Settings, locate and enable/enable the following options:

- `HdxEngine.maxPreferredServerCount` = 1

5. Click OK to apply changes.

Additional Tips for Load Balancing with Citrix XenApp

In addition to configuring data collectors as described above, consider implementing other load-balancing techniques within your XenApp environment:

* Use Citrix Director's built-in features like session monitoring and resource utilization reports to identify potential bottlenecks.

* Implement round-robin or least-connection algorithm for load balancing across multiple servers in each zone.

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By following these best practices outlined above, you can ensure a highly available and fault-tolerant XenApp 6.5 environment that minimizes disruption when failures do occur due to hardware or software issues. Remember always to test your disaster recovery procedures regularly using simulated failovers to validate the effectiveness of your design.

References

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* Citrix Knowledge Base article CTX127640 - Configuring a load balancing algorithm for XenApp 6.x and later versions.

* Citrix Online Help Center: XenDesktop VDI 7.0 Administration Guide > Planning Your Environment > Load Balancing with Citrix XenServer Essentials

Citrix xenapp 6.5 prefered and most preferred