Converged VDI Fundamentals
Wikibon research has shown that delivering software-led infrastructure as a converged appliance significantly reduces IT costs. The fewer the independent elements in the appliance stack, the lower the costs and the faster the time-to-value. If all the elements in a converged application stack are procured from a lesser number of vendors (ideally one), it also reduces the cost of deployment and the time-to-value of software implementations and upgrades.
Wikibon has also shown that delivering a converged application appliance has the potential to reduce the number of elements, increase savings, and decrease time-to-value even further. Figure 1 applies the concept of creating Single Managed Entities (SMEs) to a VDI environment to reduce operational costs and duplicate public cloud deployment economics. The Wikibon definition of SME includes:-
- An integrated delivery of the solution as a single component;
- Regular singular, globally pretested updates to the solution;
- A single business partner for sales, deployment, maintenance and upgrades;
- A single hand to shake;
- A single throat to choke.
Dell has created a Nutanix-powered single SME converged application appliance (see Note 1 in Footnotes for the official name) for VMware's Horizon View and Citrix XenDesktop solutions. Nutanix significantly reduces the cost of the storage and cluster management. Each node can be added into the rack, and the cluster recognizes additional nodes automatically and enables the resources to be utilized for additional VDI desktops with no operational intervention. This significantly reduces the complexity and risk of development, deployment, and support of the total stack software, as well as reducing the time to install new deployments and upgrades compared with the traditional “best-of-breed” white-box approach. Solutions built on top of converged application appliances require fewer integration points and reduce the number of unique problems that complicate support for vendors and users. Dell has put in place the support and extensive testing of the solutions, acts as the single hand to shake, and is responsible for the whole stack.
Wikibon Research on VDI Converged Application Appliance
The fundamental concept put forward in previous research is that a single managed entity decreases the user's cost of deployment, operations and maintenance. It also decreases the vendor's costs for maintenance and deployment. The stack that we used in our previous converged application research was application, database, middleware, OS, hypervisor, and hardware. In this research this is extended to VDI solutions, in particular with the VMware environment hypervisor. Nutanix technology is the bottom of the stack, providing the hardware and storage management. VMware vSphere and vCenter provide the virtualization layer and virtualization cluster management layer. The VDI broker runs in virtual machines under the VMware hypervisor. The Nutanix also provides the clustering technology that allows additional nodes to be added with almost no additional project cost. Dell has OEMed the Nutanix foundation block and regression tests it with the VDI brokers and has taken responsibility for the whole stack as a single deployment SME, providing asingle update, maintenance & problem resolution service. Some additional aspects (such as tying into Microsoft Active Directory) are needed for total integration into the site. So the net SME value is a little over the perfect score of 1.0.
Within the research we looked at two deployment scenarios:
- Deployment of 400 virtual desktops over three years (no increase in desktops);
- Deployment of the same 400 virtual desktops, increased by an additional 120 desktops at the beginning of years two and three.
The research analyzed the two scenarios deployed in two different ways
- A Traditional White-box Implementation Approach
- 400 VDI desktops are deployed on 6 Servers, 2.4TB Flash, and 12 TB Disk. Additional 2 servers with a proportional amount of flash and disk are deployed for each additional 120 desktops
- VMware's vSphere & vCenter are deployed for the virtualization layer
- The VMware VSAN file system is used to manage the storage
- See Table 5 in the Footnotes for all the detailed assumptions
- A Dell Nutanix VDI Appliance Implementation Approach
- 400 VDI desktops are deployed on 3 Nodes, with altogether 6 Servers, 2.4TB Flash, and 12 TB Disk. An additional node was deployed for each additional 120 VDI desktops
- VMware's vSphere & vCenter are deployed for the virtualization layer is deployed as part of the Dell Nutanix Appliance
- The Nutanix storage management and file system is part of the Nutanix software layer (including snapshots, replication, de-duplication, compression functionality).
- See Table 6 in Footnotes for all the detailed assumptions.
The most important differences between the two approaches is the full integration of everything within each Dell Nutanix Appliance node, and the ability to cluster the original nodes and additional nodes automatically and seamlessly. The most important advantage of the White-box approach is the initial lower hardware cost.
Figure 2 is a summary graph of the elapsed time and cost of the first deployment scenario (400 VDI desktops over three years). The columns on the left represent the traditional white-box approach. The columns on the right represent the Dell Nutanix application appliance (single SME) approach. The origin of this data and the assumptions are taken from detailed Tables 1 & 2 in the footnotes below. The conclusion from Figure 2 is that using an Application Converged Appliance reduces the time-to-value from 21 days to just five days, and the Dell Nutanix appliance reduces the three-year costs from $407,000 to $314,000, a savings of $93,000 dollars. The detailed assumptions are given in Tables 5 & 6 in the footnotes below and are an un-discounted cash-flow view without any depreciation. Table 3 in the footnotes extracts an IT budget view for the 400 VDI scenario from Tables 5 & 6, taking into account the depreciation on CAPEX items.
Figures 3 just below on the left shows a more detail breakout of the 400 VDI deployment scenario costs. The three-year hardware costs are more expensive by $32,000 when deploying an appliance, but the licensing cost is about $31,000 lower over three years - a wash altogether. The savings in setting up and maintaining the two environments are significantly lower for the appliance.
Figure 4 just below on the right shows that elapsed time for each stage of a project is reduced by a factor of about four, from 21 days to five days.
Figure 5 is a summary graph of the elapsed time and cost of the second 640 VDI deployment scenario, assuming the same initial 400 VDI desktops and increasing them by 120 per year for a total of 640 desktops. The columns on the left represent using a traditional white-box approach. The columns on the right represent the Dell Nutanix application appliance (single SME) approach. The origin of this data and the assumptions are taken from Table 4 in the footnotes. The conclusions from Figure 5 is that using Application Converged Appliances reduces the time to value from 37 days to just six days, and the Dell Nutanix appliance reduces the three-year costs from $533,000 to $389,000, a reduction of $144,000 dollars.
Figure 6 just below on the left shows a more detail breakout of the 640 VDI deployment scenario costs. The three-year hardware cost for the appliance is $38,000 more expensive, but the licensing cost is about $29,000 lower over three years The appliance saves $133,000 in set up and maintenance over the white box system.
Figure 7 just below on the right shows that elapsed time for each stage of a project is reduced by a factor of about six, from 37 days to six days.
Conclusions & Recommendations
One of the consistent business drivers for converged infrastructure is the business (and IT) imperative to be cost competitive with cloud services. A good overall cost metric is the cost per person-month for a VDI desktop. This is shown in Table 1 below in the "$/VDI Desktop/Person Month over three years" line item. For the 640 Desktop scenario, the cost of using the Dell converged application appliance is $21 per person-month over three years, compared with $28 for the traditional white-box approach. Using a white-box approach is 37% more expensive than using the Dell converged application appliance for VDI. Earlier research comparing a converged on-site approach to cloud approaches can be found at "Duplicating Public Cloud Economics for Microsoft Unified Communications", and shows the $21/month cost for a desktop as very competitive with cloud services.
The business case for using the converged application appliance model is also very sound. Table 1 shows the rate of return as 146% for the 640 desktop scenario, with break-even at 10 months. Table 1 also shows the CAPEX payments of the two approaches as very similar, with the converged application solution requiring 13% more capital. The OPEX is dramatically different. The traditional white-box approach requires 135% higher operating costs over a converged application appliance model.
The detail of the business case of 640 desktops is shown in Table 2 below, and is the source of the business metrics in Table 1.
The overall conclusion of this research is the Dell converged application appliance for VDI is a superior and more flexible approach that the traditional best-of-breed white-box approach, and the resulting cost of $21/person/month is very competitive with cloud service offerings with the potential for much better response times for the users.
Action Item: Wikibon research demonstrates that converged application appliances, correctly implemented, offer significantly lower costs and faster time-to-value for applications in general. Dell and Nutanix have introduced a specific converged application appliance for VDI desktops, provided by a single source, with single sets of updates, a single hand to shake, and a single throat to choke. Wikibon strongly recommends the Dell & Nutanix converged VDI application appliance be included in any RFP for VDI implementation.
Note 1 - Dell's official name for this is the marketing mouthful "The Dell XC Web-scale Converged Appliance, powered by Nutanix". Dell has a short video on its site.