XenApp 6 has now been available for about two months, and kudos to Citrix Engineering for creating the best XenApp yet. At Summit/Synergy, I made it a point to talk to partners and customers about how they planned to transition to XenApp 6. Feedback regarding XenApp 6 itself was great, but the yellow caution flags went up in discussions about the transition.

There are some concerns about the transition to XenApp 6 being that mixed farms and upgrades aren’t supported and that migration is the only option. Another major area of concern is app compatibility. Let’s address these items:

•Mixed Farms. For each of the XenApp/Presentation Server/MetaFrame product releases, warning statements about mixed farms have existed, and best practice has always been to run a native farm. These warnings statements range from potential unexpected results to multiple if/then requirements and lots of maybe’s in between. I remember working with one customer that had a mixed farm wherein custom admin rights didn’t function correctly and another one that added XenApp 5 for Windows Server 2003 to a XenApp 5 for Windows Server 2008 farm and blew up the Data Store. Many admins that survived one mixed farm never did it again.
•Upgrades: Citrix doesn’t support upgrading the operating system and then upgrading the Citrix product version, and XenApp 6 is no different. XenApp 6 is purpose-built for Windows Server 2008 R2 (and only Windows Server 2008 R2!). Not being able to upgrade the OS and XenApp version continues with XenApp 6.
•Migration: Unlike previous versions of XenApp, XenApp 6 includes a Migration Tool that will enable you to export your existing farm and app settings to your new farm. Previously, you could only export/import published app settings. This PowerShell tool is currently in beta through MyCitrix.com and will be released in a few weeks.
•App Compatibility: While 16-bit apps can’t run on a 64-bit operating system, 32-bit apps are generally fine. Research whether your concerns are real or not so real. Test your apps or use a tool such as App-DNA to determine potential app issues. If your concerns are real, consider VM Hosted Apps.

From small customers to large, I sensed apprehension about migrating to this new version. Excitement, anxiousness, and at least a few “what if’s.” It’s not a monster, it’s just new and improved XenApp.

I spent a lot of years in the field as part of Citrix Consulting, and I designed quite a few application delivery environments. While many organizations considered upgrading previous versions, a good number of them went with migrations anyway. Every new release fostered some anxiousness, but never to this extent . . . probably because this is the first time migration is the only path. Don’t panic; take a deep breath.

Let’s step back and discuss why migration is now the only option.

•Worker Group data: The Data Store for a XenApp 5 farm vs. a XenApp 6 farm differs due worker group data. XenApp 5 has no provision for this, and a business decision had to be made regarding adding functionality such as worker groups vs. mixed farm support.
•Integration with Active Directory: While XenApp has always been integrated with Active Directory, XenApp 6 takes that integration to a new level. The Group Policy Management Console can be used to administer XenApp 6. Further, when new servers are placed into OUs and automatically spun up via Provisioning services, a XenApp server can take on settings automatically.
•Operating System: Because operating system upgrades are not supported by Citrix for any component, installing a clean, new Windows Server operating system and then the new XenApp version is required anyway.
•Tech Support issues: Quite a few Tech Support issues were raised due to mixed farms, and some of these could never be resolved. Engineering could never test all of the “what if’s” that could present themselves in a mixed farm environment. So, we had customers that could never be totally content with the mixed farm approach.

While XenApp 5 is good, XenApp 6 takes on a whole new level of functionality — and hopefully now you can see why mixed farm compatibility would have been counterproductive.

Some resources you may find helpful:
CTX124481: Advanced Farm Administration with XenApp Worker Groups
CTX124241: Technical Guide to Upgrading/Migrating to XenApp 6

There are tremendous benefits to moving to XenApp 6 — a single management console, worker group functionality, improved AD integration, and much more. Give yourself a solid hour or two to work with it in your lab, and you’ll be giving thought as to how fast you can migrate to XenApp 6!