Data Center Tech Blog

VMworld Europe is next week and I am excited to be part of it! I am looking forward to meet many of you in Barcelona and discuss virtualization use cases I am evaluating.

During VMworld USA in San Francisco we received a lot of interest as well as recognition for the different virtualization solutions SanDisk® demonstrated. CRN mentioned SanDisk’s VDI solution with ULLtraDIMM SSD in their “CRN VMworld 2014: 35 Must-See Storage Offerings”, and our partner Atlantis who won “Best of VMworld 2014 Gold Award” was demonstrating their cool solution using ULLtraDIMM in their booth.

Two solution demos particularly received attention at VMworld US.  The first was our VMware VDI steady state demo of 300 users on VMware’s Virtual SAN™ (VSAN), which you can read more about here. The second  was our software solution “ioVDI” with which we did a live demo of 1500 desktops! These demos made visitors very excited about SanDisk enterprise storage portfolio and the capability of our flash solutions.

I would also like to mention the strong partnership we have with VMware. SanDisk has 21  SSD devices certified under VSAN, enabling many OEM partners and customers to build a VSAN environment either adopting “VSAN Ready Node” or “Build Your Own” deployment strategy. This is largest number of SSD devices supported by any partner.

ULLtraDIMM and VMware Virtual SAN

As ULLtraDIMM SSD and VSAN stood out for me very much at VMworld USA, I thought to build another testing setup for all-flash VSAN and consider ULLtraDIMM SSDs as a cache in combination with our SATA SSDs as a capacity layer.

We have already tested ULLtraDIMM SSD as cache for VSAN. We scaled up to 500 VDI users incorporating an application availability scenario. We found that application response time improved by 50% from VMware VDI standard benchmark (we have shared the results in our breakout session and you can download it from VMworld 2014 recorded sessions after registering ). This test showed the dramatic speed improvement of application response time in VDI environment enabled by the availability of persistent flash storage in memory channel.

VMware VDI All Flash Array Testing – Exploring Maximum Density

As VMworld approaches I wanted to share with you the current testing we are working on. In our lab we are currently testing how to scale beyond the supported limit of 100 VMs per node limit of VSAN. Our goal is to demonstrate how to achieve far better cost efficiencies with flash and to explore beyond this limitation in order to figure out the maximum VDI desktop density which would provide customers with the most efficient solution.

To carry out the testing, we choose to start the experiment with a 3-node VSAN cluster. One key element to keep in mind is that VSAN typically recommends HDDs to be used in the capacity layer. For our testing, however, we substituted our SSDs for HDDs – VMware has Knowledgebase articles outlining step by step how to do that.

So far we have built the 3-node all-flash VSAN with GA build and are evaluating the test design.

Before we start our testing I see two important things I believe need to be considered and finalized, and I’m curious to hear readers’ input and thoughts to our approach:

  1. Upgrade Horizon View from 5.3.1 to Horizon 6.0
  2. Linked Clone versus Full Clone

Upgrading Horizon View from 5.3.1 to Horizon 6.0 – this is a must. Many customers who are using Horizon View 5.3.1 might be evaluating VSAN in their environment. For them, it could be an important data point to adopt VSAN for View 6.0. View 6.0 got additional features and enhanced performance and it is worth investigating  VSAN in this new release.

Secondly, most of the desktop pools are created as floating-linked clone. This is more common for storage and management efficiency. However, from a VSAN perspective, floating-linked clone versus floating- full clone has VDI desktop scalability limitation. Let me explain this in more depth.

The “VMware® Virtual SAN™ Design and Sizing Guide for Horizon™ View™ Virtual Desktop Infrastructures”, Table 4 shows:

Screen Shot 2014-10-10 at 20.59.50(click on the image to open a bigger graphic)

This is very important to understand that even if 100 VMs per host is a soft limit, the 3000 components per host (referring to VMware VSAN Configuration Maximum Spec) is indeed a hard limit, and it will stop scaling after a certain number of VDI desktops are deployed, be it all-flash or any other solution.

The following table shows the maximum number of VDI desktops that can be accommodated using the above table (considering no disposable disk).

Screen Shot 2014-10-10 at 20.59.26(click on the image to open a bigger graphic)

You are probably be wondering why I added one more component to each case? This is because when we want to run the VDI performance benchmarking using VMware View Planner®, we need to add one additional disk in the master template that then adds one more component at the VSAN layer.

From the above table, theoretically we can scale up to 1125 VDI desktops in a 3-node VSAN cluster in Horizon 6.0. This is a huge number and will provide a very cost effective “All-Flash VDI” deployment. But there are other considerations such as User Profile (task, knowledge and power), Number of CPU cores in a system and the amount of host memory that will determine the actual VDI desktop density. I am working on the sweet spot before carrying out the tests and I hope to share the results with you soon on this blog.

If you’ll be attending VMworld in Barcelona, please join me for the solution exchange session “Virtual SAN for VDI and Enterprise Workloads” on Thursday, Oct 16, 10:50 – 11:10am.

If you have questions or feedback on our testing, please don’t hesitate to reach out to me at biswapati.bhattacharjee@sandisk.com, or join the conversation on Twitter with @SanDiskDataCtr

See you in Barcelona!

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