VDI Oh My!

This is a post originally written for the company blog — posted here for posterity.

Have you seen the cost analysis sheets from various entities over the years pointing out how much money you can save with Virtual Desktop Infrastructure (VDI)? In most cases, they’re wrong. But like most things, there are outliers. Today I want to look at VDI and break it down and tell you why you might want to use it – and why you might not. Then we’ll take a look at a few options for VDI, along with their specific advantages and maybe even a few disadvantages thrown in.

Why VDI?

  • Security: I believe that the number one benefit to any organization that VDI brings to the table is security. Security advantages to VDI include:
    • When you abstract the desktop away from the end-user environment, you also have the ability to abstract the data away and into the data center where you can better manage, backup and protect that data.
    • When you use VDI, you create a smaller attack surface. It also makes the attack surface easier to patch, update, monitor and audit.
    • Through proper policies, a VDI environment can be centrally controlled and harder to subvert – basically you have the ability to restrict data transfers, unauthorized access, and even revoke unwanted access from miles away. In the simplest terms, you can better control the number one cause of data breaches: people (Source: Baker & Hostetler, LLP. “BakerHostetler 2016 Data Security Incident Response Report”).
  • Application Management: This one may get me in trouble from VDI purists. I tend to look at VDI today as more than just delivering a desktop, and I suspect most consumers do as well. Most major VDI products have the capability to handle application package management, provisioning and access controls. What this allows you to do is maintain a stranglehold on software access and subsequently licensing usage. Licensing costs are HUGE in enterprises, and true-up and/or violation costs can be surprisingly daunting. Avoid them (or get really close) with VDI. It can make a real difference in cost. I won’t tell anyone if you don’t.
  • Availability: When you put your VDI in your data center, you are inherently gaining redundant power, UPS backup, dual connectivity and typically a better hardware class for your VDI infrastructure than you would have with haphazard desktops. Need I say more?
  • Management: Management become much easier. While I hinted at it above in the security section, it is necessary to point out that you make things easier to manage when you can update a single shared image, application or host server and have that roll out to all your users with the click of a button (or two).

Why Not VDI?

  • Security: If you are looking to invest in VDI and you do not take the time to properly secure the solution, it can be a disadvantage too. Security disadvantages to VDI include:
    • You just allowed all of your users to access their desktops from anywhere…maybe. If you have not properly locked down remote access to the right groups, secured peripheral access, and/or set up security policies, you could be opening some additional risks while eliminating others.
    • When you implement VDI using best practices, your VDI environment will become isolated from your server platforms. If you just throw VDI in without working through proper segregation, you can end up with users in the same network space as the server farms. This is generally not a good thing.
  • Management: It may be easier to manage those desktop images and you won’t need to manually go to desktops as much anymore, but the trade-off is that you’ll likely need a more skilled engineering staff to manage the underlying VDI infrastructure. With the proper staff, training, and/or the right partner (like Sentinel), you can head this off at the pass fairly well.
  • Cost: I don’t deal in money much, but I can tell you that you would be sorely mistaken to think that you will save money with VDI. You may lower either capital or operational expenditures, while increasing the other. The reality is, you are gaining features (security, application management, central management and even controlled costs) while spending the same if not more in some cases. Your mileage will vary.

Which VDI Is Best?

There are two major players in the VDI and published application world: Citrix (XenApp & XenDesktop) and VMWare (Horizon/View). Both are fully capable application and desktop delivery platforms. Citrix has the historical install base and decades of experience, but VMWare has been making leaps and bounds with their very solid product offering. VMWare owns the hypervisor space that most deployments will be installed on, yet there are some bells and whistles in Citrix that the advanced VDI deployments may need. The truth is, without sitting down and having a discussion to review your specific needs, no one can tell you which is best. I won’t try here.

Outside of the vendor platform, there is always Desktop-as-a-Service, which is available through Sentinel CloudSelect®.

Bottom Line

The bottom line is this: If you plan it well, implement it on solid technology (check out my previous article on HyperFlex as an example) with the right policies, procedures, and partner, your business and customers will be very happy. Just don’t expect to fill up a piggy bank with the extra savings.


The article here is my opinion, I wrote it.  I work for/with the companies/technologies mentioned here — if you don’t like that, tough.  If you want to learn more about Virtual Desktop Infrastructure (VDI) and determine the best solution for your business, please contact Sentinel; they pay me and that allows me to keep work on technologies like these and writing these blogs.  If you ask really nice, you might even be able to work with me.  Never know.  If you really want to help me out, contact me directly — I will get you all setup with the right people to help you out.

HyperFlex: An Enhanced Look

This is a post originally written for the company blog — posted here for posterity.

In the IT industry, the phrase “we are pretty much a 100% physical shop” is one that you dread to hear – especially from a fast-growing company. Such was the case with a leader in the financial services industry recently when they asked Sentinel to install a Virtual Desktop Infrastructure (VDI) solution for a new call center rollout of around 250 desktops as well as fully re-deploy their physical desktop and server infrastructures. They were pretty set on a hyper-converged solution and were looking for something scalable and easy to manage. To be successful, in the eyes of the business, the solution had to:

  1. Be solid. With internal hesitation to virtualization from the business, there had to be reliability.
  2. Be fast to deploy. To meet the aggressive deadlines, there could be zero delay on delivery or deployment.
  3. Be lightning fast. To aid in business buy-in and adoption, the solution had to deliver a better end-user experience than the current desktops. Performance was critical to that.

After reviewing the vendor options, the customer ultimately chose Cisco HyperFlex and VMware Horizon for their hyper-converged VDI solution. Aggressive deployment timelines were set and equipment was on the way. From there we moved onto the fun stuff.

The HyperFlex cluster was delivered quickly. Really quickly. Once the gear was on-site it was time to deploy. Before we go there, I want to touch on one particular aspect of the solution. Sentinel knows that maintaining data integrity and availability is essential to our customers as they adopt and adapt to new technology. How the Cisco HyperFlex solution delivers that can be summed up pretty easily:

  • The Cisco HyperFlex product line is a variant of the Unified Computing System (UCS) product line, and with that you have the full redundant design of dual fabric interconnects, full multi-pathing, and server hardware that is designed with zero single point of failure. In this particular deployment, we had four nodes (N+1) with dual fabric interconnects, and two 10GB paths from each of the HX240c nodes. Everything also ran on fully redundant power. It was a strong platform to begin from.
  • The SpringPath HALO Architecture is a file system – I am simplifying things here a bit – that allows for distribution of writes onto multiple solid-state drives (SSDs) across multiple nodes BEFORE acknowledging the writes. This maintains the data integrity by ensuring that there are multiple copies of the data on separate nodes in the cluster to prevent potential data loss.
  • The HALO Architecture enhances the data integrity by using a Log Structured Distributed Object Store to allocate the data as small objects across multiple servers in a sequential pattern, which are in turn replicated to other pool members to achieve data redundancy. By doing so, they increase not only performance, but the life of the flash layer disk in the servers as well as redundancy overall.

Back to the deployment. In a post on my personal blog, I mentioned that the HyperFlex deployment was pretty fast. Once you rack and cable the cluster, the HX installer is a breeze. What I love about the HX installer is the fact that it really does build the entire UCS deployment and makes adding a node to an existing cluster just as easy. Click. Click. Done. Overall, the deployment of the HX system after rack and cable took less time than installing the vCenter server that was required for the deployment (Note: The vCenter must be on separate hardware but can be moved into the HyperFlex cluster for ongoing operations).

After meeting the first two objectives, we needed to look at the speed. Since this was a VDI cluster, we made one small change (one line in a configuration file) to optimize the cluster’s L3 Cache for a read-heavy environment. Once that small change was made, it was time to run some tests. Since Sentinel doesn’t own the environment I will only include the following observations:

  • During testing of the 4-Node cluster with 4xVMs pushing I/O, the cluster achieved well over 125,000 I/Ops. Even in the worst-case boot storm of 250 users logging in within a one-minute period you would only really require 117,500 I/Ops, leaving plenty of room to spare. Keep in mind, this was not done in a controlled lab under ideal circumstances.
  • I was able to clone a 100GB (65 Used Thin) VM from template in less than three seconds. Seriously.
  • I deployed 250 linked clone desktops including two boots, customization, and domain join in under seven minutes. The bottleneck was the VDI limit on the maximum concurrent operations sent to vCenter (which I tweaked to 25) and probably the Active Directory domain join tasks as part of the customization. It was fun watching the vCenter task pane roll by so fast I couldn’t keep up with it.

The customer was extremely happy with the performance, scalability and easy management of their new infrastructure. The Cisco HyperFlex and VMware Horizon solution met the requirements so well that I better understand the hype around Cisco HyperFlex and the SpringPath HALO Architecture.

Of further interest in terms of scalability comes confirmation from Cisco that node capacity expansion beyond the current self-imposed limitation is in the works and will not be limited to hardware. External storage is also fully supported. This means you will have the capability to hyper-converge your core systems and still make use of external storage area networks (SAN) where business needs dictate.

All in all, HyperFlex is a rock solid platform with a fantastic and robust architecture that you would be wise to evaluate. Couple it with VMware Horizon for desktop deployment, and you have an infrastructure built to help your business achieve unprecedented levels of success. If you would like to learn more about HyperFlex or other converged/hyper-converged infrastructure solutions, please contact Sentinel for more information.