Atlantis ILIO Pimps Virtualized Citrix XenApp: who needs VDI?

Atlantis rightly herald ILIO for XenApp, the first solution designed specifically to accelerate provisioning, boot time and application response time for virtualized Citrix XenApp deployments into a market that some would say is quite specific.

Atlantis have evidenced reducing provisioning time, improving the user experience and reducing the amount of storage required by up to 90% for Terminal Services/Microsoft RDS workloads.

Way back in the day the Atlantis ILIO offering had some difficulties, but recent releases for both ESX and Hyper-V have seen ILIO become a common component in VDI delivery. Yet, a Presentation Virtualisation (PV) solution like Citrix XenApp is a different environment, often managed and licensed in a different way: and there is ever the question – should you virtualize XenApp? The claims on performance and density when Atlantis ILIO for XenApp is used are compelling, so will this release give a fresh impetus to virtualising RDS workloads and help with the migration to Citrix XenApp 6.5?

Virtualizing Presentation Virtualization Workloads

We’ve asked before if virtualising Terminal Services/RDS based services is sensible. In Virtualising Citrix XenApp is a Waste of Time and Effort we considered a number of benefits to virtualising Citrix XenApp servers:

  • Hardware Abstraction : As a farm changes over time it is not unusual to have a range of server hardware in use. This leads to a problem of managing and maintaining builds for different hardware platforms, different different drivers, different patching requirements.
  • Availability : While it is not possible to move individual user instances between servers, you do have ability to move servers hosting multiple users.
  • Consolidation: Application silos lead to servers being under-utilized. To have specific use PV servers consolidated together to reduce the need for ever expanding hardware. Alternatively,  new servers can be used to consolidate older servers. Running Windows 2003 standard x32 Terminal Server workloads without virtualization no longer makes sense.

A counter argument could be that terminal services workloads would often be considered as ‘requiring dedicated hardware’. But statistics from Project VRC in analysis of Terminal Services workloads running on the latest generation hardware and hypervisors show that while a bare metal server still has a small edge , the performance of virtualised servers was comparable as long as resources weren’t over-committed on the host.

Perhaps most importantly, there is an ever growing number of organisations that have invested in automating and managing their data centres by utilising server hypervisors. The default standard is to virtualise a server. Why should PV instances be different?  Tools that can help optimise and maximise that virtualisation process are key.

Citrix XenApp 4.x, 5.x and 6.0 EOL is 2013

Citrix XenApp versions 4.x, 5.x and 6.0 go EOL in 2013.  XenApp accounts for the largest user count in the hosted desktop/virtual desktop market. There is a significant install base of customers that will need to consider migrating to Citrix XenApp 6.5 with Server 2008 R2 by July 2013 unless Citrix can be coaxed into making those versions co-terminus with Windows 2003 EOL.

When customers migrate to XenApp 6.5, the majority will likely virtualize Windows Server 2008 R2 to take advantage of the manageability and consolidation benefits of server virtualization. ILIO for XenApp isn’t going to reduce the time required for that process, or help with migration from a x32 OS to x64, but there are other advantages.

Advantages for virtualised Citrix XenApp with Atlantis

Windows 2008R2 comes with far higher capabilities for user density than previous versions of Windows server. With 2008R2 servers performance issues is less likely to be with memory or CPU, and more likely to be with disk IO; which would be exacerbated in a virtualised environment using shared storage solutions.

Atlantis commissioned Shawn Bass, Citrix CTP and Microsoft MVP, to produce a white-paper, Citrix XenApp & RDS Workload Improvements by Atlantis ILIO which details a number of impressive statistics:

    • Performance
      • Provisioning – 53% faster provisioning
      • Boot Time – 4x faster boot times
      • Applications – accelerates response time of IO bound applications
    • Density
      • Server Density – 16% increase in users per server
      • Storage Density – 10x more users on existing storage
    • Storage Savings
      • Storage Capacity – reduce storage capacity by 92%
      • IO Offload – reduce IO to storage by up to 90%
      • Latency – reduce IO latency to improve response time

Compelling numbers and key to justifying the investment in the new product, as long as your virtual instances are VMware ESX. Atlantis recently announced ILIO for VDI with a Microsoft Hyper-V option, but the initial release of ILIO for Citrix XenApp only offers support for ESX.  In the main, this is unlikely to have a major consequence short term: most mature enterprise virtualisation environments host VMware.

Where there may be a difficulty is in the licensing model Atlantis have adopted. To maintain parity with their VDI offering, licensing is on a named user basis. An advantage of a XenApp environment is that licensing is on concurrent users. Microsoft RDS CALs, (a key requirement for XenApp) can be based on device  rather than user.  Both these licensing terms are well-fitted to a service where the number of devices and concurrency of users is likely far less than the number of users utilising the environment. It may well be that for enterprises operating in this way Atlantis could be open to negotiation, but I’d wonder if licensing by end-device would not be more straightforward to size and maintain.

Value Proposition of ILIO for XenApp?

A major stumbling block for VDI comes from how shared storage is sized to offer best value and good user experience. Atlantis looked to solve that issue with  ILIO for VDI. But a Presentation Virtualisation environment is much different: typically an RDS/XenApp server instance will host far more concurrent users, reduced storage per se is not going to justify the spend.

Yet, reduced storage is not the only advantage. User experience improves through accelerated response times, user density increases reducing the need for physical servers. Arguably with the licensing currently set at named user there may be a need for negotiation if your user numbers are much higher than your concurrency numbers. For small environments with a handful of VMs, it may be better to add another physical server; you’re more likely to be running Hyper-V. But, that still leaves a significant set of enterprise customers who can reduce their RDS/Citrix XenApp VM numbers and improve user experience hosted on those VMs by utilising Altantis ILIO for XenApp as they migrate to Citrix XenApp 6.5.

Does this mean this it just for a post migration environment?  With the enlightenment capability of Windows 2008R2 there is a benefit in using that OS over Windows 2003 in a virtualised environment. While Windows 2008 has this feature too, as of July 2013, the only supported Citrix XenApp version will run on Windows 2008 R2. It would appear logical then, that as there is benefit in migrating from XenApp running on Windows 2003 to the latest release. However, many organisations could well simply stick on their existing XenApp environment rather than twist to license and deploy another: or Citrix may move the EOL date to the right.   It would be useful to understand the impact ILIO for XenApp can have across a range of ‘legacy’ OSes as when deploying RDS workloads on shared storage, Atlantis ILIO can reduce storage requirements, improve provisioning and boot time and improve scalability.

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5 Comments on "Atlantis ILIO Pimps Virtualized Citrix XenApp: who needs VDI?"

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David Owen - @vmackem
Alright Mara, I must confess I can see a place for optimising application streaming infrastructure to be quicker. Ive seen a few instances where app streaming was becoming the bottleneck and the cause of bad user experiences. I guess my concern/question would be around scale. We tend not to see things like XenApp running into performance problems until customers start reaching the limits of their infrastructure, so how does ILIO for XenApp manage in a large environment? Is it reliable, scalable easy to deploy and manage? Do you see this as a tandem role out with ILIO for VDI or… Read more »
Why VMware, Citrix and Cisco loves Atlantis ILIO | Cloud Caboodle - Solutions for Virtualization and the Cloud

[…] then offered a RAM based solution with their ILIO DiskLess VDI, then presented a way to optimize Citrix XenApp instances. Atlantis’ offerings look to dramatically reduce the physical hardware required to […]


As someone who has done ILIO in many big organizations the solution works well in large deployments that seek scalable environments. For smaller and mid-sized companies, it’s not worth it.

Hardware today is cheap as long as you’re not overpaying resellers for overpriced hardware. Netapp storage, faster memory, and SSDs are dirt cheap today you can build your own high performance XA/XD server farm on the cheap and will last for many years well worth the investment than putting your eggs into these expensive mid-tier software that is adding more single points of failures.