Technical Deep Dive: XenApp Load Evaluators

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One of the often overlooked features of XenApp is truly understanding the load evaluators. As a consultant, I commonly see environments using only the Default Load Evaluator. If I am lucky, they might be using the Advanced Load Evaluator. Rarely do I find organizations actively monitoring or customizing their load evaluators.

Load Evaluators have not changed much since Presentation Server days, but amazingly they are not commonly optimized. Every environment and every workload is different, so whichever load evaluator is implemented may vary, but they should be customized and monitored.

Joining GlassHouse Technologies!

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I'm happy to announce that I have joined the team at GlassHouse Technologies as a Senior Virtualization Consultant. With this role, I will be tasked with helping manage virtualization projects, with a main focus on Citrix Technologies.

My main focus will be on expanding our XenDesktop / Virtual Desktop offerings, and will leverage all of our corporate expertise on Datacenter Management, Virtualization, Storage and Security.

The Future of Computing? BYOC!

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Check out my latest article, and in depth look at Bring Your Own Computer to Work Policies...

A growing trend in technology firms is Bring Your Own Computer (BYOC or BYOPC). Of course organizations such as Microsoft, Google, Citrix and Cisco are embracing this -- which is to be expected. However, as workforces become increasingly mobile, and virtualization methodologies are further adapted in enterprises, BYOC will inevitably grow.

Optimizing XenApp on VMWare ESX

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There are numerous benefits for running Citrix XenApp on XenServer; including single vendor support, built-in optimizations, and integration features. However, what if you are working in a VMWare ESX environment? As a consultant or an internal engineer, you cannot always dictate the virtualization environment. The following are some tried and true best practices for optimizing XenApp on VMWare ESX.

Read More, view the full article at GenV: http://www.thegenerationv.com/2009/10/optimizing-xenapp-on-vmware-esx.html

TheGenerationV.com

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I'm happy to announce that I am joining the team over at TheGenerationV.com.

I will still be maintaining my personal blog here as time allows, of course, but will also be writing case studies and analysis articles for GenerationV.

TheGenerationV.com is dedicated to hosting discussions and technical articles about next generation technology. TheGenerationV.com was founded on July 10, 2009 by Rick Rohne, however, it is made up of some of the most talented Systems Integrators in the country.

I'm looking forward to sharing my thoughts on virtualization with this team of engineers. Please come check it out.

Louisville-Area Citrix Users Group

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Chris Morgan with University of Louisville School of Dentistry has started a Louisville-Area Citrix Users Group. He and I had been discussing this for months with our regional Citrix sales management team. I'm glad to say he has taken the initiative and created a MeetUp site to facilitate this new group.

If you are a Citrix user, administrator or engineer; using Presentation Server, XenApp, XenServer, XenDesktop, NetScaler, or any other Citrix Technologies; or if you are interested in learning more, please sign up at http://www.meetup.com/citrixlouisville/

Also, as new group, we are looking for topic suggestions and vendor sponsorships. Feel free to submit any ideas you may have.

Now With MTM!

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I'm ecstatic to announce I have joined the team at MTM Techonologies as a Systems Consultant. I had the pleasure of working with MTM as a customer for many years. During this time, I had the opportunity to get to know them top to bottom. When the time came for me to make a change, this is the team I knew I wanted to join.

Quest vWorkspace

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Some time back, Quest Software purchased Provision Networks. They have sense re-branded and re-released their Virtual Access Suite (VAS) product line as vWorkspace.

Latest and Greatest: My Citrix on VMWare

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This may be my last entry on Citrix/VMWare for the time being.

After 1 month of production runs, our 1 vCPU 2GB RAM VMs are churning nicely, averaging around 32 concurrent users. Running at 10 VMs per DELL 2950 Host, we see that Host Memory is stable, Host CPU is well utilized. There is enough capacity that another 2 VMs could potentially be added with no adverse effects, netting approx 380 users per HOST... solid density.

Rolling out updated Citrix VM Template

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I have updated our Citrix VM Template:

• Added CD, left disconnected
• Updated Tools, included Memory Manager (aka Balloon Driver) -- after reviewing this time and again with various engineers, I have come to several conclusions:
• a lot of the info out there is still based on ESX 2.x
• The Balloon Driver is a safety net, which should not be normally called
  on when designed properly
• when in doubt, and until proven otherwise, go with the standard package
• Tweaked the service controls
• Added PowerShell 1.0 (I'm becoming a big fan of PS scripting)

An Interesting Day with Citrix Load Evaluators

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Ever have one of those days? Well today was it for me! We run XenApp 4.5 in 2 geographic production Zones. I get an urgent page from support that EVERYONE hitting one of our Zones was getting "... servers are reporting full load and cannot accept your connection ..." EEK!

More on Citrix Load Evaluators

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Well, most of feed back I received from other industry players confirmed my initial suspicions... counters based on Windows Perf Counters where Windows is a VM are not reliable. A local area architect, who is not married to any one technology, summed it up nicely:

"You have touched on something that is inherent to the virtual world: the performance counters are always wrong. Exactly how wrong, that is debatable. In the past, I have used empirical numbers to control load. That means keying off of something like user count, memory utilization, or page swaps. It isn't an exact science, but some testing should give you the right mix."

Citrix Load Evaluator Rules in a VM

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I mentioned in my previous post that one of my VMs was pegging at 100% of the vCPU, but the Windows Task Manager was showing only spikes (although a lot of them), and my Citrix load value for that server was in the 7200 range. Of course, the system was crawling and unusable for customers.

Update on My Citrix VMWare Machines

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Ok, if you have been following my blog, you know I have been researching and building the best possible Citrix VMs to run on my ESX Hosts. Granted, XenServer might be better for XenApp, but we work with what we have, and I have ESX 3.5.

I currently have 4 production VMs running, 2 in each production Zone. The first two in DataCenter1 went live about a month ago... and churn nicely. They will routinely show a load evaluation of 10000 (Full Load), and the 1 vCPU Utilization is fairly high (based on vCenter stats), but no complaints from users. Initial test = PASS.