Few migrations have been as thought provoking as Presentation Server 4.5 (often called XenApp 4.5) to 6.5. XenApp 6.5 was released on August 24th, 2011. Presentation Server 4.5 went end of life (EoL) March 31st, 2013. We will first look at the overview of the process of upgrading, then the core changes and finally considerations around upgrading.
How to Upgrade from Presentation Server 4.5 to Citrix XenApp 6.5
There is no solid upgrade path from Presentation Server 4.5 to 6.5 by definition. What almost all system architects will be faced with is a new parallel 6.5 farm build migration for XenApp 6.5. Since the 6.5 platform is only supported on the Windows 2008 R2 64bit architecture application compatibility becomes the paramount concern. The farm cannot be upgraded from Presentation Server 4.5 to 6.5, so the applications will have to be reinstalled on the Microsoft Windows Server 2008 R2 platform. The only Upgrade that can be done is switching application delivery from legacy to new farm. Fortunately with Web Interface and even Storefront this is a seamless process once the new infrastructure is built, tested, and ready to migrate.
Citrix Definition of Migration and Upgrade
- Upgrade: Installing a newer version of a feature or release item over an existing version.
- Migration: A clean, new installation of that feature or release item
XenApp Migration Center and Power Shell Upgrade
Citrix does provide a Migration Center and the more savvy engineer can get more granular with power shell to export setting from a legacy farm to a new farm. While technically possible this is not recommended. As with most Citrix platform upgrades it is best to start clean with a new farm build without muddying the waters. Going from the Xenapp 4 platform to the 6.5 platform is a major change with significant improvements. We will get into more of the details of the platform advantages below.
The high level overview of this process is as follows:
- Design and build a XenApp 6.5 farm with many moving pieces including those broken out below2008 R2 compatibility
- Isolation environment moved to Packaging and Streaming
- Possible hardware upgrade considerations
- Possible license issues with Microsoft and Citrix
- Application compatibility
- Upgrades to other components including SAN, Web Interface, License Server, database, and Domain
- Preliminary Testing for functionality, User functionality testing, and finally User acceptance Testing (UAT) before going live.
- Integration of the new farm with the legacy or upgraded Web Interface environment
- Application migration generally a few applications at a time to the 6.5 environment while being retired in the old 4.5 environment in unison.
From my experience doing these migrations the most encumbering piece to this puzzle is getting completely migrated to 6.5 and finally retiring the legacy 4.5 farm. The simple reason for this is vendor incompatibility with either the Windows Server 2008 architecture or the 64 bit framework. When considering a migration of this caliber be prepared to find alternatives to migrating at least 10% of your applications. In many cases this is just a waiting game until new versions of the software are released or a different platform is available such as moving a web service or onto another application platform all together. Be prepared to spend more time on this 10% of your applications than the other 90%.
Since policy can now be done through Citrix policy and AD policy it is recommended that either one or the other is used. Conflicts may occur if policy is set in both places. This AD integration of Citrix policy is new to the XenApp 6 platform.
Worker Groups are new to the XenApp 6 platform and should be carefully considered. This is a change in the way servers are managed by groups. They can be tied to AD structure to minimize management especially in larger environments. This can be very beneficial and should be considered and not overlooked as it often is.
If you are utilizing Easy Call voice services in your Presentation server 4.5 environments it is no longer available in 6.5. This is something to consider in your migration plan.
There are many reasons for upgrading to XenApp 6.5. Too many to mention in any one article. Hopefully this gives you a good overview of the product and some of the challenges. Do not feel that jumping to 6.5 is an all or nothing proposition. Even though 4.5 is end of life there are still a large majority of enterprise environments that are dealing with multiple farms. Some have even found ways to migrate to 5.0 and run a duel farm 5.0 and 6.5 hybrid environment. Until the application vendors fully support the virtualization world we will always be playing a game with some vendors in most environments of trying to fit a square peg in a round hole.
While the feature set is certainly extremely beneficial. The most value in upgrading is taking advantage of your investment. The 2008 R2 platform is proven as a solid platform. It is vastly improved over the 2003 platform. When you set the XenApp 6.5 tried and stable platform on top of it you have a very symbiotic well designed and stable architecture to launch from. Of course there are many other concerns in any environment but putting yourself ahead of the game is the key, and a 6.5 upgrade will definitely do that for you.