In the land of Citrix, what was once called "Presentation Server" is now "XenApp." Of course, there is more to this story than a name change -- Presentation Server 4.0 was replaced by XenApp 4.5, which is now being replaced by XenApp 5.0 Feature Pack 2. The name change only adds to the confusion. Citrix is trying to push bewilderment aside and tout the advantages offered by XenApp 5.0 Feature Pack 2, aiming to tap in to a potentially large upgrade market. But many systems administrators have been slow to upgrade, claiming that the upgrade process is fraught with complexities, poor support and bad documentation.
With that in mind, why would you want to upgrade from XenApp 4.5 to XenApp 5.0? According to Citrix, there are several reasons including:
- New options for virtualizing applications, including new virtual machine (VM) hosted application delivery
- Performance improvements for 3-D graphics and multimedia, accelerated network response for branch office users, as well as the ability for real-time, plug-and-play use of USB thumb drives
- Improved Active Directory profile reliability and consistency with integrated profile management
- Optimized server power and capacity, as well as significant enhancements in load management, resource allocation and control, and application performance monitoring to help organizations meet service-level agreements
- Server virtualization, integrated server provisioning and load-testing functionality to help IT meet business needs faster and on-demand
The upgrade argument becomes more compelling when moving from Presentation Server 4.0 to XenApp 5.0. Not only do you get the above improvements, but you can also garner the following enhancements:
- Innovative and flexible options for delivery of virtual applications, including offline access
- Improvements in secure application access with features like application single sign-on and a hardened Secure Sockets Layer virtual private network appliance
- Performance improvements for audio, printers and USB thumb drives
Most systems administrators running prior versions of XenApp or Presentation Server will find something of value in the move to XenApp 5, and they will want to move to Citrix's latest application virtualization product.
Adding fuel to the fire is the arrival of Windows 7, which could quickly become the de facto standard desktop operating system for many businesses that are replacing PCs. That should drive the need for XenApp 5 on two fronts: easing the deployment of applications to new PCs and supporting the new features of Windows 7.
The improvements in XenApp 5 combined with the requirements of Windows 7 will shift the "Is upgrading worth it?" question over to "What do I need to do to upgrade?" As a result, admins are going to have to confront the complex and difficult upgrade process.
But by following some common-sense rules, mixed with a little knowledge about Citrix products, most systems administrators should be able to tackle the upgrade and avoid the common "gotchas."
First off, engineer an upgrade plan. That plan will include an inventory of the server hardware, the applications that are virtualized, the implementation and design of any existing XenApp/Presentation Server configuration, the desktop operating systems in use, and the server operating systems in place. That information will help administrators to decide on an upgrade strategy. Most upgraders will choose one of three paths: an in-place migration, an upgrade or a clean install.
Those looking to install new servers or extensively upgrade hardware as part of their XenApp deployment will want to pursue a clean install, basically starting from scratch. Although a clean install still requires extensive planning, Citrix offers extensive documentation and support. Upgrades, on the other hand, involve installing a newer version of a feature or release item over an existing version and be the most problematic course to follow. Even Citrix's documentation states that "where feasible, migrations are preferable."
While clean installs may be the most straightforward method of going to XenApp 5.0 Feature Pack 2, a migration could be the best way to move from Presentation Server 4.5. Migrations combine some of the simplicity of a clean install with the benefits of an upgrade. But an in-place migration still poses several chores and complexity.
So why go through the hassle?
The answer is surprisingly simple: An in-place migration preserves the existing virtual applications and simplifies licensing and application deployment to desktop PCs in the enterprise. Systems administrators who choose to conduct in-place migrations will need to prepare for several hours of downtime for their virtualized applications.
Naturally, one of the first steps before attempting a migration is to completely back up the existing Presentation Server/XenApp systems and then verify those backups to recover quickly if a migration fails. Another important task is to review the new terminology used with XenApp because many of the older terms associated with Presentation Server have been renamed. Not understanding the new terminology and how it relates to existing features can lead to confusion during a migration.
Citrix offers several example configurations and a preconfigured XenApp evaluation environment that upgraders can access to test-drive the product's new features and capabilities. Better yet, admins should consider doing a few "test" migrations in a lab environment to avoid unforeseen issues.
The migration process is accomplished in several steps, which Citrix defines as:
- Install or upgrade Citrix Licensing Server.
a. Add licenses and/or verify that Subscription Advantage date is Sept.18, 2009, or later.
- If new installation and enterprise-grade database to be used for data store, install and configure.
- Install or upgrade Zone Data Collector(s).
- If legacy Resource Manager is used, install or upgrade Farm Metric Server(s).
- Install or upgrade XenApp member servers.
- Install or upgrade Web Interface server(s).
- Install or upgrade other features/components.
Each of these steps requires administrative intervention, and not all are driven by wizard-type installers. In the past, many people were critical of Citrix for not publishing in-depth upgrade documentation, but with XenApp 5, that has changed. Citrix offers several pieces of support documentation, which go into further detail for particular migration situations. However, that documentation can be somewhat difficult to locate on the company's website. Here are some direct links to those bits of information:
- Technical Guide for Upgrading / Migrating to XenApp 5.0
- Citrix XenApp 5.0 for Microsoft Windows 2003 Server Upgrade Checklist
- Citrix XenApp 5.0 for Microsoft Windows 2003 Server Upgrade Guide
- Citrix XenApp 5.0 for Microsoft Windows Server 2008 Installation Checklist
- Citrix XenApp 5.0 for Microsoft Windows Server 2008 Installation Guide
With some careful planning, experimentation and due diligence, upgrading to Citrix's latest and greatest virtualization tools should not present any major difficulties -- as long as systems administrators are prepared.
ABOUT THE AUTHOR:
Frank Ohlhorst is an IT journalist who has also served as a network administrator and applications programmer before forming his own computer consulting firm.