You want to virtualize XenApp. Really?

Daniel Feller over at Citrix posted this great article about virtualizing XenApp environments.  In my ten years of architecting XenApp infrastructures, I get this question just as often as Daniel.  If I had a dollar for every time I had that question, I wouldn’t be working or writing this post…

Here is part of Daniel’s post:  Enjoy!!!

Being a Sr. Architect within Citrix for almost a decade, I’ve been asked by more Citrix administrators than I could ever count, wanting to know if they should virtualize their XenApp environment.  My typical response, which is common for a consultant, was “It depends.”   Unfortunately, this is not an easy yes or no question.  XenApp is a unique beast in the delivery center.  Users don’t interact indirectly with a XenApp server like they do other systems (database, web, etc). Instead, users work on the servers directly.  And if the servers have been designed appropriately, they should reach their memory limit or CPU limit.

Let’s say, for example, your business is to write screenplays for “The Simpsons” and you have a set of XenApp servers hosting a single application for storyboarding.  This application is critical to the business.  On average, throughout the day, the CPU is 60% utilized and the memory is 80% utilized (4GB on Windows 2003 Server).  What advantage would you gain by virtualizing this system?  The hypervisor WILL take resources.  Chances are slim you would be able to host a second virtual server on this physical system.  In this case, I don’t see where server virtualization fits. You could add more memory and additional CPU sockets, but you are spending more money just to try to save money.  Of course there are some XenApp servers that are underutilized.  Why?  Was it an improper design? Or was there a business reason? With underutilized severs, we do have the opportunity to reduce the XenApp hardware footprint somewhat.  But in my opinion, server virtualization is trying to solve a small problem in the XenApp world, consolidation.  With proper hardware design, this can be mitigated. I have seen, based on my experience as a consultant and an administrator, the bigger challenge is management, availability and flexibility.

Read the rest of the post here

~ by Michael Keen on May 16, 2008.