Daniele Tosatto

The following registry changes are recommended for all deployment scenarios and would almost always be desirable in a Windows 7 hosted VM-based VDI desktop implementation:

Note: The Optimizer column indicates whether this registry change is included in the XenConvert Optimizer tool that is installed with the Provisioning Services target device software.

Standard Mode Recommended Configurations

The next set of registry changes are recommended for images deployed using standard mode vDisk images with Citrix Provisioning services. Standard mode images are unique in that they are restored to the original state at each reboot, deleting any newly written or modified data. In this scenario, certain processes are no longer efficient. These configurations may also apply when deploying persistent images and in many cases should be implemented in addition to the changes recommended in the preceding section.

Optional Configurations

This last set of machine-based registry changes is optional regardless of whether the image is deployed as a persistent or standard image. In many cases, the following configurations should be implemented; however, these configurations should be analyzed for suitability to each unique environment.

Note: These are only recommendations. You should implement these at your own risk

Remember, you can stay current with this and other Windows 7 virtual desktop recommendations via the Virtualize My Desktop – Windows 7 site.

Virtual Reality Check (VRC) Project, the independent benchmark validated by both Citrix and VMware, is back with a new project: VDI Smackdown.

The 33-pages free report is a feature comparison of the four major VDI platform available on the market: Citrix XenDesktop, Microsoft Windows Server 2008 R2 Remote Desktop Services, Quest vWorkspace and VMware View.

The document highlights the key points that should be considered when customers define their VDI strategy.

You can download the whitepaper here.

If using hosted shared desktops or hosted VM-based VDI desktops, those virtual desktops are located within the data center with other critical systems.  If a virus made it into the data center, the entire infrastructure is at serious risk.  However, simply adding an antivirus solution to the virtual desktop can protect the environment. So what’s the big deal? Just do it right?  Well, nothing is as simple as one expects it to be.  Antivirus can have a major impact on the virtualization infrastructure, and even cause users to experience poor virtual desktop performance, if done improperly.

If the virtual desktops are streamed with Provisioning services, and those desktops start a full system scan at roughly the same time. Provisioning services only streams the portions of the disk image that are required.  However, if a full system scan is done,  those virtual desktops will eventually request the entire vDisk image. This not only overwhelms the network and Provisioning services, but also impacts the storage infrastructure as the write cache is utilized and explodes in size. Overcoming these issues is a fairly easy matter and is based on the following recommendations:

1. The desktop image must be free from viruses. It is recommended to do a full system scan in private image (read/write) mode. This guarantees the image is clean.
2. When the desktop image is in standard mode (read-only), the antivirus should be configured as follows:
   1. Only scan create/modify activities of files
   2. Scan on write events only
   3. Scan local drives only
   4. Exclusions
      1. Pagefile
      2. Print Spooler directory
      3. Write cache file
      4. EdgeSight database
      5. ICA client’s bitmap cache directory
   5. Remove the antivirus configurations from the HKEY_LOCAL_MACHINE\Software\Microsoft\Windows
      \Current Version\Run registry key
3. Reconfigure antivirus so that the virus definitions file is stored on a persistent disk so antivirus doens’t have to download the entire definition file on each startup.

The RD Virtualization Host Capacity Planning in Windows Server 2008 R2 is now live on the Download Center.  This white paper is intended as a guide for capacity planning of RD Virtualization Host in Windows Server 2008 R2. It describes the most relevant factors that influence the capacity of a given deployment, methodologies to evaluate capacity for specific deployments, and a set of experimental results for different combinations of usage scenarios and hardware configurations.

Citrix releases an interesting white paper discussing Best Practices for HDX Technologies for XenDesktop.

You can find it here .

Here you can find some useful resources to plan and design Citrix environments.

The following resources provide a best-practices based approach to designing virtualization environments based on Citrix XenApp and XenDesktop technologies:

• Windows XP Optimization Guide for Virtual Desktops
  Description: If Windows XP is still your desktop operating system of choice and it is going to be used within a virtual desktop environment, you need to optimize it appropriately. The optimizations will help deliver a better user experience and greater scalability on the hypervisor of choice (XenServer, Hyper-V, or ESX).
• XenDesktop Modular Reference Architecture
  Description: The architecture explained within this white paper is a recipe for creating a scalable XenDesktop environment using any required FlexCast option. This reference architecture discusses how to configure the controllers, imaging layer, application layer and the desktop layer.
• High-Availability for Desktop Virtualization – Reference Architecture
  Description: In environments where desktop virtualization is a critical business resource, it is imperative that the solution remains available even if a component or data center is lost. This reference architecture looks at all levels of the entire XenDesktop solution, and provides an architecture for creating a highly-available solution.
• High-Availability for Desktop Virtualization – Implementation Guide
  Description: Implementing a desktop virtualization solution oftentimes requires an investigation and implementation of the high-availability options. This white paper provides step-by-step instructions for enabling high-availability in XenDesktop within a single site and across multiple sites.
• Virtual Applications or Virtual Desktops
  floirDescription: Trying to decide between virtual desktops and virtual applications is oftentimes challenging. By understanding the core expectations and requirements for each delivery method helps make this decision easy. This white paper focuses on the decision and how to identify the most appropriate type of delivery solution.
• Networking topics, including Global Server Load Balancing- it’s like never having to worry about datacenter failures again.

Citrix has realesed XenClient after a long period of beta testing.

Here you can find more information about it: http://www.citrix.com/English/ps2/products/product.asp?contentID=2300325

XenClient is a high-performance, bare-metal hypervisor that enables users to run multiple instances of an operating system simultaneously, side by side, and in complete isolation. XenClient uses the same core technology as Citrix® XenServer®—a proven technology widely acknowledged as the fastest and most secure virtualization software available. To ensure the highest levels of performance for the user, XenClient builds on Intel® vPro™ hardware virtualization technology.

Citrix® XenClient™ enables virtual desktops to go. Desktop virtualization is rapidly being adopted as the best way to deliver Windows® desktops to business users. Now, organizations can extend the benefits of desktop virtualization to mobile users, for new levels of portability and security. With XenClient, laptop users can take multiplevirtual desktops with them and work from anywhere, anytime.

Intel IT conducted an internal technology evaluation to determine how using the most up-to-date hardware and software, such as Intel® Xeon® processor X5570 and Microsoft Windows 7, affects server and network utilization as well as the performance of streamed and virtual hosted desktop (VHD) compute models. This study followed a previous investigation, published in 2008, that compared streaming and VHD.1 Evaluation indicates that streaming provides better server loading and a more positive overall user experience with new Intel® Xeon® processors.

Click here for read the paper

Here you can find some interesting points:

• For basic office productivity applications, systems based on dual-core processors with streaming provided a 26 percent better WorldBench 5 performance benchmark score than VHD.
• Streaming server utilization was consistently low. Streaming used about 1 percent of the processor while VHD used from 10 to 70 percent or more for up to 40 PCs.
• A richer graphical user interface(GUI) with more features in Microsoft Windows 7 contributed to higher cumulative network traffic for both streaming and VHD, up to a 57 percent increase in traffic for 20 users.
• Using WorldBench 5 tests as the primary indicator, local computing using the latest technology provided the best user experience.

How often did you wish there was a way to change the GUID on a virtual desktop agent without manually going to the registry or running a repair on the VDA agent? Well Citrix Support team is pleased to provide you another useful tool to do that and more …
It is called the XenDesktop VDA farm Changer!

This tool can scan Active Directory to find available Farms, provide a dropdown list of the available farms along with the ability to change farm membership, displays current farm membership, displays VDA and/or ICA client version, provides an interface to all VDA system services along with service status, and provides other data points and frequently used shortcuts for VDA management.
You can download this tool here in http://support.citrix.com/article/CTX124379

Microsoft has introduced a new MMC snap-in tool called Remote Desktop Connection Manager in Windows Server 2008 R2 for managing the in-box VDI solution from Microsoft. In this blog, I will explain how you can specify various RDP settings for the virtual desktops published using this tool.

You can specify a different set of RDP settings for each type of virtual desktops (Personal and Pooled) published by this tool.

To modify RDP settings for “Personal Virtual Desktops,” expand the “RD Virtualization Host Servers” node, select “Personal Virtual desktops” and then select “Properties” from actions.

To modify the RDP settings for pooled virtual desktops, select the pool node under “RD Virtualization Host Servers” node and then select “Properties” from actions. This allows you to change the RDP property for the pool that you have selected. If you have more than one pool of virtual desktops, you will have to change RDP settings for each pool by going to their respective nodes.

For most common RDP settings there is a “Common RDP Settings” property tab with dedicated UI controls for each of the setting. The “Custom RDP Settings” tab allows you to specify advanced RDP settings which are not modified very frequently. Given below is an example of how Custom RDP Settings can be used to enable optimal audio/visual experience for virtual desktop users.

Enabling optimal user experience

By default, the virtual desktops published through this tool are tuned for performance. For example, with default RDP settings, users will not be able to see the wallpaper on their virtual desktop. To enable the optimal audio/visual user experience, you can add following RDP settings under the “Custom RDP settings” tab:

With the above settings, RDP connections to virtual machines require higher network bandwidth compared to default settings. Therefore the admin should enable these settings taking into account the available network bandwidth and the desired user experience.

For a complete list of RDP settings for Remote Desktop Services, see the Remote Desktop Services Technical Reference (http://go.microsoft.com/fwlink/?LinkId=139899).