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August 30, 2013

Best Practices: Powering VDI Performance for optimal virtual desktop performance

Andrew Wood - Atlantis


A key factor in a successful virtual desktop deployment is a great user experience. To ensure this is delivered, all components of your architecture need to optimally configured. The memory, the storage, the network and the compute performance.

When working with customers for proof-of-concept and pilot environments, I’ve found it common to be presented with a set of servers (or server) that have been excitedly  un-boxed and plugged in. Alternatively during the process of helping to solve performance issues, its not unusual to find the simple things got overlooked.

Microsoft MVP and Citrix CTP Helge Klein, in his informative blog on  HP power profile on vCPU performance stated that when you buy a new HP server it comes with the BIOS setting HP Power Profile set to Balanced Power and Performance. As Helge states that sounds good, but it’s bad: at least for CPU performance in a VDI environment. There is also a detailed set of information on power settings for Hyper-V from Microsoft MVP Didier Van Hoye on Considering CPU Power Optimization vs Performance When Virtualizing  with a good follow-up.  I can confirm that servers from vendors other than Dell and HP I’ve seen have the same default power configuration and can befit from changing settings.

Power Management Settings Impact on Virtualised Workloads

Disabling power management can result in more power being consumed by the system, especially when it is lightly loaded. Yet, for a virtualized desktop environment you will rarely be “lightly loaded”.  To deliver the best value for money you want to correctly size your servers hosting virtual desktops so that every CPU cycle and MB of RAM is utilized.

A power efficient BIOS setting limits the performance of virtualized workloads on the server making ‘balanced’ a very false economy. That’s not good. Not good in a virtualized desktop environment where the user directly interacts with the virtualized instance and you want to deliver the best possible performance.  Of course, the better the performance the more likely that users will be besides themselves with glee and you will have a successful deployment.

VMware recognise that poor virtual machine application performance may be caused by processor power management settings, Microsoft understand that overall performance of Windows Server 2008 R2 can be degraded and Citrix give recommendations on how to configure XenServer Host’s BIOS Power Regulator for Maximum Performance.


Atlantis ILIO Powering  VDI Performance

Atlantis In-Line I/O Optimization, Atlantis ILIO, is a 100% software solution that optimizes storage provision for virtualized workloads. As a 100% software solution, as a software appliance, it is very simple to integrate into your environment and, as a software appliance, Atlantis ILIO is indeed a virtualized workload itself. While an Atlantis ILIO appliance typically requires little CPU resource, having that extra performance that the optimised BIOS settings brings can deliver greater performance.

Now here at Atlantis Computing we can do impressive things. For example, here was one customers SAN results after testing with our recommended VDI  Iometer testing configuration.


When we introduced Atlantis ILIO in an in-memory configuration in this particular environment, where Atlantis ILIO is offering memory as a primary tier of storage, the customer was able to deliver the following:

However, from experience of deployments in similar environments I knew those figures, while impressive, could be better. Given the impact that BIOS power settings have on virtualized workloads we checked the PoC server BIOS settings: which were in fact set to be conservative. Optimising the power settings in-line with the best practices guidelines from the hypervisor vendor resulted in:

Atlantis ILIO driving IOPS performance

The customer knew that for each server in their solution they could deliver at least 30,000 IOPS. Nice.  And, throughput increases and latency improves. Nicer. And, that vCPU performance gain would be replicated across each and every virtual desktop. Nicest.

With Atlantis ILIO and optimised BIOS settings you can not only improve compute performance, but improve your storage performance. These improvements combine in a virtualised desktop or hosted desktop environment to a give that great user experience which is a key for success.

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